So, 2 days ago I switched out 275/40/18 toyo t1s to 295/35/18 toyo t1r on the rear. Since then, I have experienced some weird problems. I was driving to work yesterday at about 70 mph and took a curve to the right. When I turned the wheel to follow the curve my car did what felt like a strong oversteer to the right. I corrected and it felt very "wobbly". I thought maybe I had a flat or something, because the car did NOT feel like it did the day before when I had the 275s on. I should also add I have the Hotchkis stage1 suspension setup on my car. I do not get any oversteer under normal conditions. I just dont know what it could be that is causing this. I looked over my suspension with a fine toothed comb last night and found nothing wrong. Checked all my tire pressures just in case and they are all at 37.5psi. What the hell could be wrong? Could new tires make a car feel this much different? I used to be so comfortable driving at high speeds, but now with this steering issue, I am scared to go above 70 without being super careful. HELP!

 

try giving it a few days to kinda break in the tires.

 

are the tires brand new? you may need to drive them around a bit to burn off the slick coating that is put on new tires.

 

+1

The tires are quite slick until you put a few miles on them. I just put a new set on a couple of days ago and had a similar situation. I accelerated hard in second gear in a slight turn, and the car began walking sideways. After I put 100 miles on them I've had no porblems.

 

+2 on breaking in the tires. I heard this is especially the case on the T1-R's.

But what's weird is, I would tend to think you would exhibit understeer since you got fatter tires on the rear...

 

Agree--the silicone used for the tire mold is very slick. That's a huge problem with new motorcycle tires. Lots of guys crash their bikes if they don't break the tires in for 100 miles or so. Toyo seems to have more initial slickness than most, so I've heard.

 

You know, I see what you are saying. But this is definatly oversteer... I am a big fan of pushing my car to its limits on the turns, and this did not feel like that. It felt uncontrollable and scary.
However, this does make sense about breaking them in. I am glad to hear it should go away. I was begining to think I might have to buy new 275's to get the old feel back! Should I go easy on them while breaking in? Or is normal/aggressive driving fine?

 

No. With slippery tires in the rear he'd be getting oversteer. When the tires break in and get stickier, then he might get some understeer.

 

That makes sense. I just assumed he swapped out the front as well, but just for the same size as he had before. But if the front tires are older and stickier than the rears (or rears are still not broken in), then yes, oversteer is a possibility. Now I'm thinking the stagger front to rear is greatr than before since he probably kept is old front tires and only got wider rear tires. That should theoretically lead to understear.

Actually, his oversteer resulting from slicker rear tires + understeer from wider rear tires should cancel everything out.

 

haha if only it worked that way! I did keep my 245/40/18 t1s up front as they still have 40% life left on them. I will be upgrading them in the upcoming months, as well.

 

Two words for you...smokey burnouts.

 

I was just gonna say that Burn those bad boys abit

 

ok...
so...
first off..
what size rim is this going on..
i had the same issue before when i was running too ride a tire for a wheel
and it made the handling a little loose due to severe sidewall flex..

 

these are on 9.5's... I was a little concerned with this issue myself. Hoping this isnt going to be a problem! They are SLIGHTLY too big for the rim but I was looking at the greddy test car and they run 305's on a 9.5 rim so I didnt think it would be a huge problem. SAY IT AINT SO!

 

That is what I did when I got new tires. Problem solved in less than 30 seconds!

 

So, although what you guys are saying does make sense. I think I went too big with my tire choice. I spoke with anotheraznguy and he informed me he had a similar problem when going to 305s on a 10inch rim. The problem I described was identical to his problem. Therefore im gonna be forced to sell these tires and go back with 275's. THIS SUCKS. I really dont want to have to do this but I am selling the 295s in private classifieds.

Link: https://my350z.com/forum/showthread.php?t=180697

 

What is your wheel width? If it is to small you could have to much roll over which would explain your problem.

Before you sell it, look at the manufactures web site for recommended wheel width range. If you are in that range, than you need to brake the tires in. If you are outside that range, then sell them.

 

I am running 18x9.5 in the rear and those are the rims holding the 295/35/18's

 

i believe the suggested rim width for 295s are 10-11.5".
but like mooddude said, check out toyos website to double check.

 

It's so. A 295/35 needs to be on at least a 10 inch wheel. Optimal is 10.5.

Chris