Rear tire wear on s2000

[240260280z]

Yokohama AS430 on rear went bald in center after 7,000mi.

I read some website content and some say it is due to too much rear toe -in and others say it is "too low" tire pressure (which conflicts with rule of thumb that excess tire pressure causes center wear). My initial tire pressure was 30psi when stock is 32. I dropped it to 28psi when I noticed the wear but it did not make a difference.

Rear toe-in is 6mm

Any comments?

Edited July 21, 2011 by Blue

[Gary in NJ]

7,000 miles. Outstanding. The fastest set of tires I ever wore down were Michelin Pilot Sports (245/40-17) on my 330Ci at 11,000.

Some cars just eat tires. I was able to increase my mileage to 17,000 per set by driving a bit more conservatively and keeping the tire pressure up.

My 2004 Silverado is kind to it's tires. I got 70k out of the first set and at 110,000 miles I have lots of life remaining on the second. Of course, acceleration and lateral g's are not in its play book.

[Jeff G 78]

Looks totally normal. S2000's eat rear tires at an alarming rate. My dad's S2000 wears tires very quickly, though they do wear much more evenly than yours. Honda runs a lot of rear toe for stability, but I'm no S2000 expert so I can't say what happens if the toe is reduced. NSX's wore tires out in ~3,000 miles for the same reason.

[jmortensen]

Toe in wears the outside of the tire.

Toe out wears the inside of the tire.

Just think of how the tire rolls when the tires are toed in or out and this should be pretty intuitive.

Pos camber wears the outside of the tire.

Neg camber wears the inside of the tire.

Same here, pretty intuitive.

Underinflation wears both sides of the tire, but not the middle.

Overinflation wears the middle of the tire, but not the sides.

If the tire is overinflated it won't retain it's squared tread shape and the middle wears faster. If underinflated there may not be enough pressure to push the middle of the tread flat on the ground and the edges wear faster.

http://www.procarcare.com/includes/content/resourcecenter/encyclopedia/ch25/25readtirewear.html

If the tires were not overinflated, the next most likely thing I would say would be too wide a tire on the rim. If you force a 255 onto a 6 inch rim (gross exaggeration) the tire can't sit flat on the road and will drive on the center of the tread very similarly to an overinflated tire.

[30 Ounce]

My Z used to wear it's rear tires at about 10,000 miles and the fronts would look brand new. I had about 1/4" rear toe. Went to adjustable lower control arms and 0 toe and problem solved. My rears looked exactly like yours.

[jmortensen]

Then your tires were overinflated or too large for the rims. If the tire is sitting flat on the ground, an incorrect toe setting will HAVE TO wear the inside or outside edge of the tire first.

[LeonV]

I think it's the combination of rear toe-in and negative camber that causes the middle wear. Setting rear toe to zero will likely solve this problem but it might create another. I know S2000s can be twitchy so setting rear toe to zero, from a previously toe-in setting, may make it less stable during hard driving.

[jmortensen]

Doesn't jibe with my experience. I used to align Porsches for a living, they all have neg camber and toe in in the back, I can't say that I ever saw wear that pronounced in the middle of the tread only and a lot of them were stuffing tires that are wider than they should be on the rim too. Toe in will wear the outside of the tire unless the outside of the tire is off the ground due to a ridiculous amount of neg camber. Neg camber will always wear the inside of the tire, and not the middle. Those tires look square to the ground but the middle is worn. That indicates overinflation or way too wide a tire on the rim.

That tire has a treadwear of 440. Something has to be really screwy for it to wear out the center in 7K. What size tires are on it? Stock rims?

[Arne]

Years ago when I dealt with tires for a living, Honda's engineering philosophy appeared to be to always use as narrow a rim as possible. For example, when VW was putting 175/70-13 on a 5.5" rim, Honda was putting that same size on a 4.5" rim. Similar story later - GTIs had 185/60-14 on a 6", CRXs had the same size on 5"; later on Accords had 205/60-15 on 5.5" while the rest of the world used up to 7.0".

Looks like they might still think that way. I know the rear size on most S2000s is 225/50-16 - how wide are the rear rims?

[Jeff G 78]

I just looked it up Arne. They use a 16x7.5 in the rear with a 225 tire. I have read though that their 225 tire is on the wide side of nominal, so when switching to a non-OE tire, a 235 is needed to keep the original tire width.

I agree with Leon that it is a combination of toe and camber that's causing the center wear. Toe will wear the outside, but that wear will creep inboard with a lot of camber.

EDIT: A quick search on a SK2 forum reveals that toe is the culprit. The setup I found was to use the low end of the toe spec and 2° of camber in the rear. Less toe alone will cause oversteer. The added camber helps the situation. YMMV. (literally )

Edited July 21, 2011 by Jeff G 78

[LeonV]

I just looked it up Arne. They use a 16x7.5 in the rear with a 225 tire. I have read though that their 225 tire is on the wide side of nominal, so when switching to a non-OE tire, a 235 is needed to keep the original tire width.

I agree with Leon that it is a combination of toe and camber that's causing the center wear. Toe will wear the outside, but that wear will creep inboard with a lot of camber.

EDIT: A quick search on a SK2 forum reveals that toe is the culprit. The setup I found was to use the low end of the toe spec and 2° of camber in the rear. Less toe alone will cause oversteer. The added camber helps the situation. YMMV. (literally )

Bingo, nice find!

[jmortensen]

Not buying it. 6mm is a lot of toe in. A lot. But you would have to have a huge amount of neg camber to wear the tires out without catching the outside of the tread. If the neg camber was sufficient to allow the toe to wear the tires in the middle but not on the edge, the the tires would be worn out on the inside, and they appear to be just fine. Something else is going on here.