Poor Handling New Tires need Help.
 

last night I had my rear tires changed on my 02 C5 convertible w/ 15kmi. I had them changed to Toyo T1R's in 275-40R18 (stock size). The fronts are still the stock GoodYear Run Flats. Anyway, on the way home the car is handling like crap.... like the back tires are flat and rolling on the sidewall. So I check the pressure monitoring system, it states all pressures are in check. Not trusting it I get out and check it w/ my gauge, everything is about 35 psi. I check the tire rotation.....that was correct, look for loose lugs, etc. Everthing seems fine. So I keep heading home over a twisty moutain road. The car sways and rolls hard in the corners. So I start testing it a little on a straight section of road and jack the wheel left and right like running through cones..... not too hard though and active handling engages..... I've never had it do this with the run flats or at least I never noticed it. With some straight road left I rip thru the gears and at just over 100 the car feels like it is barely on the road, like it is floating. I had the car at 150+mph the other day w/ the GY run flats and felt 100 times better than it did at 100 last night.

I did a lot of research on this tire and a lot of guys love them on their vettes. A poll on Z06vette.com has about 33% of the people using them. So I don't like it's just a cheap crappy tire.... if it didn't get good reviews I wouldn't have bought them.

Could it be.
- Mixing the run and non-runflats?
- run flat side walls stiffer than the toyo thus causing it to roll?
- Mold release on the tires causing them to slip (it didn't feel like it was slipping more rolling)?
- something happend to the suspension and it's just a coincidence that it happened when I had the tires changed. (specilized shop did it not walmart)
- could there be some belts broken in the tire (the guys did seem to have trouble getting the one tire to pop on beed in about a 2" section)
- do they need to break in a little.... I only went about 30 miles with them.

when I say they handle bad I mean it rolls almost like my SUV (well not that bad) but 100x worse than before I brought it in.

I need some help here guys. Anyone else running this tire and having problems.

THANKS!!!

RE: Poor Handling New Tires need Help.
 

First of all, you should never mix runflat and non-runflat tires (get rid of the runflats, ASAP!). Secondly, 35 psi is way too high. 28-30 psi cold is the recommended pressure. I've seen a guy (in a C4) wipe out on a curvy mountain road because he accidentally inflated his tires to 35 psi. But primarily, your problem is the mixing of tire types. Runflats have extremely stiff sidewalls compared to normal tires.

RE: Poor Handling New Tires need Help.
 

I don't think 35psi is WAY TOO much. The door slicker calls for 30 cold and 35 hot. I'm going to put a buddies run flat rims and tires on over the weekend and see it it comes back. If so, it's the tires and I'll order Toyo's for the front. However, I want to try the run flats again before I just start ordering stuff.... plus it's any easy swap.

RE: Poor Handling New Tires need Help.
 

Not too long ago, a shop that did some work on my Mazda MX6 GT had overinflated the tires to 35 psi. I thought I was driving on plastic donuts - steering was super-light and handling was a bit scary. As soon as I deflated the tires, handling was restored. In your case, I believe it's a combination of overpressure and two types of tires. Let us know what happens.

Dave

RE: Poor Handling New Tires need Help.
 

I'm going to try and few things. First I'm going to lower the rear tire pressure to 28-30 psi and see what that does. Then I'm going to toss my buddies rear wheel w/ GY runflats on my car and see if handling is back in order as it was when I brought the car in ............... want to rule out damaged suspension. If that test goes well I'll be ordering T1R's for the front and cross my fingers :)

thanks guys. I'll keep you posted.