Biggest tire size w/out a lift - Page 2 - Jeep Compass Forum
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post #31 of 105 Old 09-29-2018, 01:52 AM Thread Starter
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Originally Posted by Chris Jacobs View Post
Don't focus on how much tire was added here look at the height and width of the tire.



Michael Guerrera, started off with 215/65/16 which are 27" tall and 8.5 " wide. The 225/70/16 are 28.4" tall. So in his case he moved up 1.4" He could do that without rubbing because he started with a 27" tall tire.



Because I'm starting with a 28" tall tire I don't think I can add 1.4" of tire pretty sure a 29.4 " tall tire without a lift would cause all kinds of issues. What I'm paying attention to is that he posted a 28.4" tall by 8.9" wide tire is clearing everything without issue. For me that is if I could find a tire in a 17" that was 28.4" tall that would only increase my tire height by .4" but the closest I can find is a 225/65-17 which is .5 inches taller with the same 8.9" wide. Looking our Trailhawk over I can see the extra .1" should fit just fine.



As near as I can tell there were at least 1 more 17" size tires listed for a 2018 Compass besides the Trailhawk it looks to be a 225/60-17 or 27.6" tall 8.9" wide. But again as far as fitting without rubbing total tire height and width is what to look at and not how much larger than stock the tires are. Something I have not thought about here is backspacing on the rims I want to find out if backspacing and rim width is the same or works out to the same. I'm sure in my case I will be fine but if others have different backspacing and width it could throw things off a bit. So I still advise measuring as I pointed out in post above.





As for MPG this is where height over stock matters as it changes the last gearing figure in your drivetrain. In theory your going to lose some city and gain some highway with a slightly larger tire. How much depends on how much you change your tire size your driving style and tire choice. The weight and rolling friction of the tire will change from tire to tire. There is a point in increased tire size where both city and highway MPG will suffer but we are not talking anything near those sizes here. I have seen little effect in MPG on any of my vehicles where I bumped up tire size by an inch or less. On my 03 Chevy Tracker I increased tire height by ~2.6 inches I lost 3 MPG city and gained 2 MPG highway. But each vehicle will be effected differently because of gearing/weight actual tire selection and other variables. I don't see bumping up tire height by less than an inch really hurting our MPG on our Compass very much at all if we select the right tires.



I would try to avoid heavy ply tires like those used for heavy duty trucks unless your wheeling were you need a heavy thick tire they tend to weigh a lot and this combined with extra height is going to really put a dent in your MPG.



A quick look at Tirerack.com shows the stock 215/65-17 Falken Wildpeak tires on our Trailhawk weigh 27 lbs. In a AT 225/65-17 I can get a BFGoodrich KO2 tire which is a great AT tire but it weighs 39 lbs and I'm not sure a lighter ply is available in this size for this tire. This tire is going to cost a lot MPG in stop and go traffic and because it is a heavy load range it will ride rough on something lighter like our Compass. Then I looked at other tires in the same size to compare weight and I find a Pirelli Scorpion AT weighs in at 29 lbs this weight wise would be ok on MPG. It is a lighter ply tire so ride would not suffer too much. However I personally do not like the looks of it to me the Wildpeak looks better. But I'm still looking at tires and with only 10k on stock tires I have plenty of time to shop to find a tire that will be the best all rounder for us.



These are all the same things you should be looking at if ride and MPG really matter to you. So when your tire shopping look at the load range and weight of the tires. For MPG try to find tires around or less than 30 pounds each.

With a 17” rim size, it seems we can only go from the stock 225/60/R17 to a 225/65/R17 and that means going from 27.63” diameter to 28.52”. I don’t know if anyone tried these bigger tires yet. All we know so far is that 28.40” fits well...
About the loss in mpg with these tires, and using your numbers from your old Chevy Tracker, that means that if we increase the diameter in about 1/2”, we will loose about 0.57 in mpg in city.
If the Compass has a city mpg of 23, then, we will have maybe 23.57 mpg?


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post #32 of 105 Old 09-29-2018, 03:36 AM
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With a 17” rim size, it seems we can only go from the stock 225/60/R17 to a 225/65/R17 and that means going from 27.63” diameter to 28.52”. I don’t know if anyone tried these bigger tires yet. All we know so far is that 28.40” fits well...
From what I see on our Trailhawk stepping up to a 28.5" tall and 8.9" wide should not be an issue But again with the Trailhawk we start with a 28" and it has different struts and possibly springs.

Michael Guerrera does not have a Trailhawk and reports the 28.4"tall and 8.9" tires fit fine I don't think that .1 difference in height would have caused him any issues he can likely tell us how tight the 28.4" tall fits. But really it is what like a 10 of an inch so if we don't have that to spare we need not change tire size at all as a little dirt in the wheel well would be an issue.

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About the loss in mpg with these tires, and using your numbers from your old Chevy Tracker, that means that if we increase the diameter in about 1/2”, we will loose about 0.57 in mpg in city.
If the Compass has a city mpg of 23, then, we will have maybe 23.57 mpg?
I wish the math was just that simple I was just using my Tracker as a lose reference. My Tracker is much much lighter than the Compass and gets like 4.87 axle ratio. It also runs a 2.0 engine and 4 speed auto. While going up to a so much larger tire screwed with the last number in drive ratio I had a lot more gearing in my favor. Then with less weight I was not having to move much weight with that taller gear ratio.

With our Jeeps I don't know how all the variables will play out. The 9 speed transmission is much more computer intensive so it might adapt better. Then the whole gearing thing. The Trailhawk has better gearing to handle a slightly larger tire than other trim. However it is also around 300 lbs heavier which will hurt it a with the taller tire around town an climbing hills. I still hold that increasing tire size 1" or less will cost very little MPG. Again though I'm talking about tires that are not way heavier than stock. Toss those 39 lbs BFG tires on there it is going to kill your city MPG or when your climbing a hill. It is just too much rotating weight for a Compass.

We are getting 23 MPG summertime with our Trailhawk on wife's work commute which is absolutely terrible for getting decent MPG. If I had to guess what jumping up .5 inches in height on our tire size will be on MPG on her drive it might drop to around 22.5. But on the interstate around 75 MPH we tend to get 27-28 MPG. With the taller tire I'm thinking we will pretty much gain our losses back maybe a tad more due to lower RPM. All this assumes we keep the tires around the same stock weight.

So keep the tires on the lighter side and I think you will likely gain back on the interstate what you lose city unless you never have places you drive with long stretches with no or very few stops and a speed limit of 55-75. Keep in mind unless you get your computer programmed for the larger tires your MPG display and odometer will be off. So to know what your really getting your going to have to hand calculate MPG by hand using math to account for the tire size increase.
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post #33 of 105 Old 09-29-2018, 02:49 PM Thread Starter
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From what I see on our Trailhawk stepping up to a 28.5" tall and 8.9" wide should not be an issue But again with the Trailhawk we start with a 28" and it has different struts and possibly springs.



Michael Guerrera does not have a Trailhawk and reports the 28.4"tall and 8.9" tires fit fine I don't think that .1 difference in height would have caused him any issues he can likely tell us how tight the 28.4" tall fits. But really it is what like a 10 of an inch so if we don't have that to spare we need not change tire size at all as a little dirt in the wheel well would be an issue.







I wish the math was just that simple I was just using my Tracker as a lose reference. My Tracker is much much lighter than the Compass and gets like 4.87 axle ratio. It also runs a 2.0 engine and 4 speed auto. While going up to a so much larger tire screwed with the last number in drive ratio I had a lot more gearing in my favor. Then with less weight I was not having to move much weight with that taller gear ratio.



With our Jeeps I don't know how all the variables will play out. The 9 speed transmission is much more computer intensive so it might adapt better. Then the whole gearing thing. The Trailhawk has better gearing to handle a slightly larger tire than other trim. However it is also around 300 lbs heavier which will hurt it a with the taller tire around town an climbing hills. I still hold that increasing tire size 1" or less will cost very little MPG. Again though I'm talking about tires that are not way heavier than stock. Toss those 39 lbs BFG tires on there it is going to kill your city MPG or when your climbing a hill. It is just too much rotating weight for a Compass.



We are getting 23 MPG summertime with our Trailhawk on wife's work commute which is absolutely terrible for getting decent MPG. If I had to guess what jumping up .5 inches in height on our tire size will be on MPG on her drive it might drop to around 22.5. But on the interstate around 75 MPH we tend to get 27-28 MPG. With the taller tire I'm thinking we will pretty much gain our losses back maybe a tad more due to lower RPM. All this assumes we keep the tires around the same stock weight.



So keep the tires on the lighter side and I think you will likely gain back on the interstate what you lose city unless you never have places you drive with long stretches with no or very few stops and a speed limit of 55-75. Keep in mind unless you get your computer programmed for the larger tires your MPG display and odometer will be off. So to know what your really getting your going to have to hand calculate MPG by hand using math to account for the tire size increase.


I suppose that when you say 0.5” more on your tire size, you are talking about 0.5” increase in the radius which will be 1” increase in diameter, right?
Considering the Compass Sport comes with a 17” rim, I can only go from 225/60/R17 to 225/65/R17 and that means a 0.89” increase in diameter. We only have that report about 25.4” diam tires fitting well, but in my case, I will end up with a 25.52” diameter. I still don’t know if I will get some rubbing...


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post #34 of 105 Old 09-29-2018, 03:59 PM
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I suppose that when you say 0.5” more on your tire size, you are talking about 0.5” increase in the radius which will be 1” increase in diameter, right?
Considering the Compass Sport comes with a 17” rim, I can only go from 225/60/R17 to 225/65/R17 and that means a 0.89” increase in diameter. We only have that report about 25.4” diam tires fitting well, but in my case, I will end up with a 25.52” diameter. I still don’t know if I will get some rubbing...


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No we are looking at the total height of the tire which is the diameter so in my case with having 215/65-17 moving to a 225/65-17 is a .5 inch increase in diameter. In your case you are starting with a shorter tire so overall increase is more. Our starting points don't matter for tire fitment as long as the rim size and backspacing is the same because in our Compass there should not be a change in wheel well measurements between different trims. I might have slightly different gap between tire and fender well than you or Michael Guerrera simply because I have a Trailhawk and it shows as different struts and likely springs from other trims.But I doubt it will amount to much at all.

Where stock tire size does matter is in how far your speedo will be off and in the effect on MPG as tire size increases but again under 1" it will not throw things too far out of whack. The tire size calculator I have been using shows the 215/65-17 as 721 revs per mile the 225/65-17 comes in at 708 revs per mile so like 13 more revolutions in a mile difference. Yours will be off slightly more as your moving up from 225/60/R17 which interestingly means your tire width will not increase where mine will go from 8.5 wide to 8.9 wide.

Here is a link to the online tire size calculator I have been using it has other calculators linked to on the site that are useful as well that can show you things like how far your speedo will be off in changing tire sizes. Play around with a bit on here lots of great tools and they will show you some tires in the size your looking at.

https://tiresize.com/calculator/
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post #35 of 105 Old 09-29-2018, 11:41 PM Thread Starter
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No we are looking at the total height of the tire which is the diameter so in my case with having 215/65-17 moving to a 225/65-17 is a .5 inch increase in diameter. In your case you are starting with a shorter tire so overall increase is more. Our starting points don't matter for tire fitment as long as the rim size and backspacing is the same because in our Compass there should not be a change in wheel well measurements between different trims. I might have slightly different gap between tire and fender well than you or Michael Guerrera simply because I have a Trailhawk and it shows as different struts and likely springs from other trims.But I doubt it will amount to much at all.



Where stock tire size does matter is in how far your speedo will be off and in the effect on MPG as tire size increases but again under 1" it will not throw things too far out of whack. The tire size calculator I have been using shows the 215/65-17 as 721 revs per mile the 225/65-17 comes in at 708 revs per mile so like 13 more revolutions in a mile difference. Yours will be off slightly more as your moving up from 225/60/R17 which interestingly means your tire width will not increase where mine will go from 8.5 wide to 8.9 wide.



Here is a link to the online tire size calculator I have been using it has other calculators linked to on the site that are useful as well that can show you things like how far your speedo will be off in changing tire sizes. Play around with a bit on here lots of great tools and they will show you some tires in the size your looking at.



https://tiresize.com/calculator/


I am concerned about the fact of not having any evidence on having 225/65/R17 tires on the Compass 2018. Will I have some rubbing? Even if they fit ok in the wheel wells, could passing over a road bump be an issue?


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post #36 of 105 Old 09-30-2018, 10:59 AM
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If your this worried about the slightly larger tire not fitting just get a nice all terrian tire with good tread blocks in the stock size.
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post #37 of 105 Old 09-30-2018, 04:16 PM
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I am concerned about the fact of not having any evidence on having 225/65/R17 tires on the Compass 2018. Will I have some rubbing? Even if they fit ok in the wheel wells, could passing over a road bump be an issue?


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That is why I have said you should take some measurements with your Jeep flexed. If you have a hill or some drive on work ramps you can pull each corner up onto the hill or a ramp and this will work your suspension so you can look at clearances with the tires you have now. look at how much room you have to spare then you will know for sure. Just be safe and use wheel chocks and set the parking brake.

My biggest concern was the funky clearance in the rear fender. Luckily I have a pretty sharp hill next to our driveway. I just drove up it off camber till I had wheel spin. So I had 1 front wheel compressed and one rear wheel compressed the other 2 are unloaded/drooped. In fact I could lift the unloaded rear wheel off the ground with 2 fingers. With the parking brake set I got out and just look at how close the compressed rear wheel was to the fender I did this on both sides. I still need to compress each front and check with wheels turned full lock each way but I don't see any issues just looking at it. I would tell anyone looking to bump up on tire size to do this because if you go on the Mopar parts page there are several different spring part numbers listed. This means some of these Compass might have different ride heights from the factory. Different spring rates will also flex differently with suspension travel as well.

For me I think I could go a full inch taller in tire but it would be closer in fit than I want it to be. Plus I really don't want to go much taller than stock because of it throwing off gearing and speedo. The only reason I want to change tire size is because in a 215/65-17 all terrain tire selection sucks! It is only a bit better in the 225-65-17. But I'll take the 1/4" of added ground clearance as a bonus.
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post #38 of 105 Old 10-01-2018, 12:28 AM Thread Starter
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That is why I have said you should take some measurements with your Jeep flexed. If you have a hill or some drive on work ramps you can pull each corner up onto the hill or a ramp and this will work your suspension so you can look at clearances with the tires you have now. look at how much room you have to spare then you will know for sure. Just be safe and use wheel chocks and set the parking brake.



My biggest concern was the funky clearance in the rear fender. Luckily I have a pretty sharp hill next to our driveway. I just drove up it off camber till I had wheel spin. So I had 1 front wheel compressed and one rear wheel compressed the other 2 are unloaded/drooped. In fact I could lift the unloaded rear wheel off the ground with 2 fingers. With the parking brake set I got out and just look at how close the compressed rear wheel was to the fender I did this on both sides. I still need to compress each front and check with wheels turned full lock each way but I don't see any issues just looking at it. I would tell anyone looking to bump up on tire size to do this because if you go on the Mopar parts page there are several different spring part numbers listed. This means some of these Compass might have different ride heights from the factory. Different spring rates will also flex differently with suspension travel as well.



For me I think I could go a full inch taller in tire but it would be closer in fit than I want it to be. Plus I really don't want to go much taller than stock because of it throwing off gearing and speedo. The only reason I want to change tire size is because in a 215/65-17 all terrain tire selection sucks! It is only a bit better in the 225-65-17. But I'll take the 1/4" of added ground clearance as a bonus.


Unfortunately, I can’t do all these testings to check how much extra clrearence I have because I still don’t own a Compass. I am planning to buy a 2018 Compass Sport and to go directly from the dealer to a tire store and trade the stock tires for bigger ones.
I currently own a Jeep Liberty and I changed the stock tires for higher ones and it all worked well.


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post #39 of 105 Old 10-01-2018, 03:53 AM
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Unfortunately, I can’t do all these testings to check how much extra clrearence I have because I still don’t own a Compass. I am planning to buy a 2018 Compass Sport and to go directly from the dealer to a tire store and trade the stock tires for bigger ones.
I currently own a Jeep Liberty and I changed the stock tires for higher ones and it all worked well.


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Ok now I have a better understanding of your situation. Have you considered moving up to the Trailhawk trim. LOL

Here is another thought that might make everything work out for you. If I was in your stituition and stuck with getting a Sport trim I'm guessing new. I would see if you could talk your dealership into fitting a larger tire and reprogramming the ECM for the tires while making sure your warranty stays intact. You will be surprised what a dealer will do to get you to sign on the line especially if it look like you are going walk away. I had my dealership install a factory hitch on our Trailhawk and that cost them pretty much the same as installing new tires would. It is worth the try anyhow.
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post #40 of 105 Old 10-01-2018, 01:28 PM
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Great info! Which tires did you end up going with and as always pics would be great!!!!

Just for reference for others 225/70-16 on the tire size calculator comes in at 28.4" tall and 8.9" wide. A 225/65 17 is almost exactly the same and comes up as 28.5" tall and the same 8.9" wide so fit should be the same just less sidewall height. Again though different shoulder types and brands may size and fit differently.
Went with some Wranglers. I live at the New Jersey shore and in the fall/winter off season months were able to drive onto the beach for some surf fishing. The extra traction feels great. Took her up on the beach for the first time yesterday and she handled it with ease. The 4x4 lock in Sand mode is just money.

Heres some pics! Happy to answer any questions

https://imgur.com/a/NZKdYFz

side note - switched out for LED head lights and DRLs. Just has a more premium look. Also blacked out all badges and added black door handle covers. Think the black accents looks sweet with the olive green.
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post #41 of 105 Old 10-01-2018, 02:35 PM Thread Starter
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Went with some Wranglers. I live at the New Jersey shore and in the fall/winter off season months were able to drive onto the beach for some surf fishing. The extra traction feels great. Took her up on the beach for the first time yesterday and she handled it with ease. The 4x4 lock in Sand mode is just money.

Heres some pics! Happy to answer any questions

https://imgur.com/a/NZKdYFz

side note - switched out for LED head lights and DRLs. Just has a more premium look. Also blacked out all badges and added black door handle covers. Think the black accents looks sweet with the olive green.


Nice! What size are those tires? No issues on bumps? How about increase in mpg?


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post #42 of 105 Old 10-01-2018, 03:03 PM
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Nice! What size are those tires? No issues on bumps? How about increase in mpg?


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As previously stated, they are 225/70/16's. No issues on bumps and no rubbing whatsoever. Chris is right, another .1" up isn't going to hurt you. There's enough clearance, but its close. I wouldn't go too much larger.

As far as MPG, I believe Chris answered that as well. You're going to lose some city and gain some highway. But it's barely noticeable. I usually average around 25-26 per tank of gas. Which is fine by me. Going 65-70 on the highway and I can clock in around 38-40 MPG if i'm rocking cruise control.
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post #43 of 105 Old 10-01-2018, 03:14 PM Thread Starter
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As previously stated, they are 225/70/16's. No issues on bumps and no rubbing whatsoever. Chris is right, another .1" up isn't going to hurt you. There's enough clearance, but its close. I wouldn't go too much larger.



As far as MPG, I believe Chris answered that as well. You're going to lose some city and gain some highway. But it's barely noticeable. I usually average around 25-26 per tank of gas. Which is fine by me. Going 65-70 on the highway and I can clock in around 38-40 MPG if i'm rocking cruise control.


Would you share with us photos taken from the side to show how much room is still left on the wheel well with your 28.4” diameter tires?
Thank you!


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post #44 of 105 Old 10-04-2018, 02:46 AM Thread Starter
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From all the wheel wells, I am most concerned with the rear ones on the front side of the tire that is too close to the fender as can be seen on this photo. If I go with a 225/65/R17 which adds 1/2” more to the tire radius, will it be extremely close and dangerous to the fender?




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post #45 of 105 Old 10-20-2018, 01:12 AM
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Just had 235/65/17 Aturro Trailblade XTs installed on my 2015 Compass Sport... running stock rims. NO RUB, Very little highway noise. Look and ride great
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post #46 of 105 Old 10-20-2018, 01:15 AM
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New tires 235/75/17 Aturro Trailblade XT
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Looking good
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post #48 of 105 Old 10-20-2018, 02:17 AM Thread Starter
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225/65/17’s:



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post #49 of 105 Old 10-20-2018, 01:49 PM
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So how much clearance do you have left in the rear wheel well?


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225/65/17’s:



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post #50 of 105 Old 10-20-2018, 05:08 PM Thread Starter
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So how much clearance do you have left in the rear wheel well?


About 3 cm on the outside where the fender is and just 1/2” in the inside where there is a protrusion in the plastic that covers the wheel well. (On the rear tires)


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post #51 of 105 Old 10-20-2018, 07:07 PM
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New tires 235/75/17 Aturro Trailblade XT
Just to clarify for everyone, this is a 1st Gen Compass.

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post #52 of 105 Old 10-22-2018, 04:34 PM Thread Starter
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I finally changed the stock tires for a bigger size 225/65/17 and after 5 days, I had the Low Pressure tires warning on the dashboard. I checked the tires and in fact, they were low. I put more air and kept the 35 psi on the front and 32 psi on the rear, but the readings on the dashboard were 34 psi on the front and 31 psi on the rear. Now, a day later, I start seeing 33 and 30 on one side... seems like they are loosing air? What can it be?


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post #53 of 105 Old 10-22-2018, 04:44 PM
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Bad/damaged valve stem?

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Biggest tire size w/out a lift

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Bad/damaged valve stem?

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The car is brand new and the tires I purchased were supposedly brand new as well? Could it be that they were defective? For some reason, the guy at the Continental tire shop traded off the tires with me saying he didn’t want any money in exchange... I am worried now...


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Last edited by HernĂ¡n Grimberg; 10-22-2018 at 08:39 PM.
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post #55 of 105 Old 10-22-2018, 07:55 PM
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Take them back and have them investigate. Shouldn't be any issue if they were properly installed and were new, good tires.

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2018 Jeep Compass Lattitude - Billet Silver, 4x4
2014 Jeep Grand Cherokee Limited, EcoDiesel - GONE
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post #56 of 105 Old 10-22-2018, 09:11 PM Thread Starter
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Biggest tire size w/out a lift

It is so weird, the tire pressure readings on the dashboard fluctuates all the time. From 35 psi on the front, it goes down to 33 psi and then back to 35 psi some time later. Same on the rear, from 32 to 30 psi and back... what is happening here?


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post #57 of 105 Old 10-22-2018, 11:14 PM Thread Starter
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I just went to the tire shop and we submerged the tires in water and no air bubbles were coming up...


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post #58 of 105 Old 10-22-2018, 11:51 PM
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You realize there's expansion and retraction when a tire is cold and hot

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It is so weird, the tire pressure readings on the dashboard fluctuates all the time. From 35 psi on the front, it goes down to 33 psi and then back to 35 psi some time later. Same on the rear, from 32 to 30 psi and back... what is happening here?


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post #59 of 105 Old 10-23-2018, 12:18 AM
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It is so weird, the tire pressure readings on the dashboard fluctuates all the time. From 35 psi on the front, it goes down to 33 psi and then back to 35 psi some time later. Same on the rear, from 32 to 30 psi and back... what is happening here?


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As tires heat and cool the PSI in the tire changes this is very normal and if you have never driven something with a constant tire pressure monitoring system then you have never seen this effect in real time. This is also why often as late fall and winter come in and outside temps drop we end up having to add air to our tires.

Mine tripped the TPMS a few mornings ago for all 4 tires. I drove it for bit because the tires were not that low once warmed up. Both fronts showed like 27 PSI cold and came up to 33 PSI warm. Rears were like 28 PSI and would come up to to around 30-31 warm.

The difference from front to rear has to do with workload on the tires the front has a bit more weight and does the majority of work on the Compass steering,braking and under acceleration. So the fronts heat up first and the most!

After all 4 tires were inflated to 35.5 PSI the fronts will now go up 39 PSI and the rears to like 37 I think. This is the first time I have had a vehicle that constantly displayed tire pressure. I knew this relationship between tire temperature and PSI existed this is the first time I could watch it in action and thought it was kind of cool to watch Again perfectly normal. Something I did discover after the TPMS trips the displayed low PSI and TPMS comes on is that it take a little bit of driving maybe an 8th or so of a mile before the new PSI is displayed and the TPMS warning goes off.

BTW, Tires look great on your Compass!!!
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post #60 of 105 Old 10-23-2018, 01:26 AM Thread Starter
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As tires heat and cool the PSI in the tire changes this is very normal and if you have never driven something with a constant tire pressure monitoring system then you have never seen this effect in real time. This is also why often as late fall and winter come in and outside temps drop we end up having to add air to our tires.



Mine tripped the TPMS a few mornings ago for all 4 tires. I drove it for bit because the tires were not that low once warmed up. Both fronts showed like 27 PSI cold and came up to 33 PSI warm. Rears were like 28 PSI and would come up to to around 30-31 warm.



The difference from front to rear has to do with workload on the tires the front has a bit more weight and does the majority of work on the Compass steering,braking and under acceleration. So the fronts heat up first and the most!



After all 4 tires were inflated to 35.5 PSI the fronts will now go up 39 PSI and the rears to like 37 I think. This is the first time I have had a vehicle that constantly displayed tire pressure. I knew this relationship between tire temperature and PSI existed this is the first time I could watch it in action and thought it was kind of cool to watch Again perfectly normal. Something I did discover after the TPMS trips the displayed low PSI and TPMS comes on is that it take a little bit of driving maybe an 8th or so of a mile before the new PSI is displayed and the TPMS warning goes off.



BTW, Tires look great on your Compass!!!


Ok, so it is normal to get a tire pressure warning due to this normal fluctuation in temperature. This means temperature can create a differential in air pressure of more than 25%.
The other question I have is that given the fact that I increased the size of my tires from 225/60/17 to 225/65/17, will I have to put less air pressure on my tires? Is there a formula so you know how much less to keep the air volume constant?


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