The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

Tire Wear Question

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Hello:

I experienced unusual tire wear at Mosport this weekend. At the end of the weekend I noticed that the passanger side front tire of my Conti GT-O's had corded and started to delaminate on the inside edge. The other three tires and the middle and outside of the suspect tire all have consistent wear with around 2/32nd's remaining. I was running them at 31lbs cold and 36lbs hot all weekend. They were purchased new and had about 15-18 sessions with very even wear at the start of the weekend. Does this sound like a defective tire or an alignment / setup issue? Suspension is stock with camber bolts (camber at the last alingnment was 2.0 degrees).

Thanks,
Sean
 
1,022
99
Exp. Type
HPDE
Exp. Level
10-20 Years
Texas
15-18 sessions sounds like a descent amount of life from the tire. Depends on the track layout/car setup/staggered vs square/driving style on how your tires will wear and which one will go first. If you are running square rotating the tires will help prevent this and promote more even wear.
 
They were new when purchased and had plenty of tread left at the start of the weekend, as well as 2/32nds remaining on the 3 other tires (and the center and outside of the damaged one). They are / were rotated at each event. My past experience with new Cont's is that I'd easily get 25+ sessions before ethe wear makers were gone or the were heat cycled out. I expect this set would have heat cycle out before the tread was gone, but with what's left on the rest of the tire(s) I should have gotten another 8-10 sessions. There is either something wrong with my alignment or a defect in the tire. I just can't think of a setup issue that would cause such excessive wear on the inside 2 inches of the front passanger side tire on a track with mostly right hand turns.
 

Grant 302

basic and well known psychic
Mike has a good point about spring rate, but the problem may also have been your camber settings for Mosport.

I'm going to guess that you were running CCW and/or that the course has at least one high speed left-hander. Not sure if you could have identified the wear issue earlier in the day and adjusted your camber a bit on the driver side.

Doesn't look like there's anything wrong with the tire per se.
 
There are 2 high speed left hand corners at Mosport. Where I'm getting confused is what would be the correct alignment change to eliminate the inside of the passenger side front from wearing like it did. I was only running about 2-2.2 degrees of negative camber (which is the most I can get with camber bolts)...any less wouldn't seem to make sense and more would exacerbate the issue, wouldn't it?

Mike was there with me...he has cc plates with -2.7-8 degrees of camber (I believe). He was running Parelli slicks. The tire and .5 degree of additional camber make it hard to compare, but He didn't have any noticeable increase in wear on the inside front passanger tire.
 
KBBOSS1086 said:
There are 2 high speed left hand corners at Mosport. Where I'm getting confused is what would be the correct alignment change to eliminate the inside of the passenger side front from wearing like it did. I was only running about 2-2.2 degrees of negative camber (which is the most I can get with camber bolts)...any less wouldn't seem to make sense and more would exacerbate the issue, wouldn't it?

Mike was there with me...he has cc plates with -2.7-8 degrees of camber (I believe). He was running Parelli slicks. The tire and .5 degree of additional camber make it hard to compare, but He didn't have any noticeable increase in wear on the inside front passanger tire.

Also hard to compare as I have a stiffer springs, a stiffer front sway bar and my 305 tires are mounted on 11" wide rims.
 
I definitely think the ultimate spring rate has something to do with it...soft springs, compressing a longer distance in left hand corner would cause the tire to raise / rotate up and in, causing the tire to ride more on the inside edge.
 
KBBOSS1086 said:
I definitely think the ultimate spring rate has something to do with it...soft springs, compressing a longer distance in left hand corner would cause the tire to raise / rotate up and in, causing the tire to ride more on the inside edge.

My thoughts exactly. Your car is leaning due to soft spring rates and sticky tires, in turn causing the non-loaded side of the car to raise up leaving just the inner portion tire of the tire in contact with pavement.
 
6,363
8,187
IF these were Contis, or Pirellis I would say this....
Add more camber, softer rear springs, stiffer fronts and go less front air pressure, a lot less front air pressure.Blue bar, in the center link and the small or no bar in the rear.
Depending on the ambient starting temp, go read the tire technical article that's a sticky at the front of this page, and determine your starting pressure when cold.
You also need to take temps across the face of the tire
 
Thanks Everyone.

Rob: The tires are Conti GT-O's (305 / 660 /18's FWIW). I do have a front set of coilovers ready to go. Once I save enough $ for rears I will be installing them. The front have 475lb springs. I'm planning to go with 250 or 275lb rears. I haven't pulled the trigger on a front bar but I do have a Strano 3 way adjustable that I will start on the softest setting. I was able to take temps across all tires. The inside and outside were within 2-3 degrees...the centers were 8-12 lower. After that I added 1lb of air pressure. Unfortunately, I got distracted and didn't check the temps again after the pressure increase.

I've been running slicks for several years now and have always experienced very even wear and long life. When I look at the tracks I run a lot at...Watkins Glen and Pocono vs Mosport (this was my first time there), one thing stands out. The high speed turns at WGI and Pocono are not downhill and have lots of banking. At Mosport they are downhill and have much less banking. Point being, I think the banking at the other tracks has lessened the negative effects on the inside of the front tires. The flatter downhill high speed turns at Mosport may have revealed one of the weaknesses of a soft setup on slicks. I will have to wait till next year to see if the changes outlined above will correct the problem, but I feel pretty good that it will.

Thanks agiain.

Sean
 
Sean, I had the same problem at Mosport with my Nitto NT01's. I had the insides cord very similar to yours. I had the wear on both sides. They were pretty even. I was also running 2.0 deg of neg camber with stock springs & shocks. May also look into stiffer springs once budget allows. Glad you enjoyed Mosport it's at the top of my list for next year.
 
Hermes said:
Sean, I had the same problem at Mosport with my Nitto NT01's. I had the insides cord very similar to yours. I had the wear on both sides. They were pretty even. I was also running 2.0 deg of neg camber with stock springs & shocks. May also look into stiffer springs once budget allows. Glad you enjoyed Mosport it's at the top of my list for next year.

Thanks for the info, Hermes. It's good to know that this likely isn't a problem that's unique to my car / setup. I should have the suspension upgraded before I go back next year, so we will see if that corrects the problem.
 
1,022
99
Exp. Type
HPDE
Exp. Level
10-20 Years
Texas
You'll also have to play with camber settings. Unfortunately if you want to get the most out of the tire you would have to optimize the camber for each track. I have corded both the inside and outside of my tires and sometimes I get lucky and they cord at the same time which to me means I had the camber set perfectly. One other thing to think about is if you are running a lot of negative camber you can cord the insides due to friction under braking. If you are running square rotate your tires often. I rotate tires at the beginning of every day in an "X" pattern. Good luck
 
6,363
8,187
On the mustangs the front tires, never..ever...sit flat, basically they are cambered in, then , even with that, they roll over enough to burn off the outer edges. You are probably not running enough camber, and the coilovers need to be about 300 (or so) rear and 600 (or so) front. we run no or the smallest bar possible in the rear. I'll try to post up some pics of our cars in decel and acceleration.

This was the 6 cylinder car at COTA
5uzwZLCl.jpg

The GTS car at COTA in mid corner
7W3nZJ2l.jpg

The GS car with Contis at Kansas
HppZFD2l.jpg

The GTS car at Laguna Seca
hAbl2hDl.jpg

The point is, we never seem to get enough camber, also the temps need to be done as soon as the car comes off the track...lok for around 230 maximum and adjust from there. We get within tenths of a pound on all 4 corners. .4 is my goal in pressure.
 
Thanks Rob. I totally get what your saying. What is confusing me though, is that the wear in the pictures is on the inside of the right front not the outside...and with only 3 left hand turns at Mosport I would expect more wear on the left front not the right.
 
6,363
8,187
We use an asymmetrical setup there, and you have wayy too much air pressure...OR.. the pressure is spiking because it's not nitrogen but instead air, with too much humidity in it.
Look at the pic with the Contis, in some shots, especially the rear, the wheel rim is almost touching the ground, it wasn't uncommon to grind the continental sticker off of the tire. The Pirellis, not so much because of the different construction, but the Pirellis we use have a different construction between front and rear tires, also the size is a 660-18 up front and a 680-18 in the rear.
 
Thanks again Rob. I will have to try a lower pressure...been running 28-29 cold and 34 hot. I've run numerous sets of new Conti's over the past few years with the identical setup and similar pressures and never saw this happen. The only variable in this case was the track (first time at Mosport). With everything being constant and the few left turns at the track I'd never imagine the inside of the right tire to wear that badly, even if the pressure was a somewhat high. Especially since I've always gotten very even wear on all of my previous sets with the identical setup and similar pressures. This is why my first thought was that it may be a defective tire. I haven't seen a tire peel like it has in the pictures above either.

I will be upgrading the suspension for next season and will try lower pressures, but I'm still baffled why this happened now, without the slightest indication of uneven wear in the past. Oh well...
 

TMO Supporting Vendors

Top