I've got 245/50/16 tires on my GT rear. They are wrong for the GT. So instead of tossing them in the garbage, or wearing them down, which might take me two years, I thought I'd put them on my rear 7 inch phone dials on my '79 car. I know this is WAY off from the maximum 1.15 ratio. It's more like a 1.2 ratio.
After searching the archives, I found that someone was racing with 235's on 7.5 inch wide wheels.

I also posted this in the wheels forum, but I trust you guys.

 

We have a local who's been driving his '85 7-in's all-round for years with 245's. He's happy, been on-track and has experienced no problems. However when I look at them, they look like balloons. Fugly.

 

Bernard, I hear you. And I thank you for setting me straight on the GT. I'm putting stock tires on that car, thanks to you. In fact, I don't think anything else would even fit inside the fender. But I've been a money sprinkler. It's thousands here and thousands there. I just can't eat this one. Can you give me a specific reason why I should not use these tires on my '79?
They might have sidewall flex that will make me dislike them. But that's all I can come up with.

 

Greg a 10 inch wide tire pinched down onto a 7 inch wide rim just plain looks BAD and should handle poorly as well . Is it "safe"? probably never now the difference in 99 % of your driving . That last 1 % is where the rear end passes the front end when you push it very hard in a corner . But mounting and balance is not much money IF you want to try it but please find the limit with the current tires (possibly old dry dead ones) then try the wide tires ....same corner , same speed ...let us know the results

 

Being a cheapskate can work sometimes. And sometimes it can lead to the Darwin award. Noone would buy used tires, and I'd never toss them. So I'll try them and see how they work. But I will do so with the knowledge that Darwin is watching.

 

Gregg,

I put my old tires on Craig's list and someone bought them for their
Mustang (225/50-16 and 245/45-16)s. In fact, he said he would have
preferred 245/50-16s on the rear.

( http://sis125.berkeley.edu/928/tires/ )

 

I have 245/50ZR16 on the 7" wide trashcan lid rim, it really improved the handling of the car, the @$$ doesn't like to come around on me anymore.

 

I just bought 4 new wheels for my 1980 928. The size of them are 245 45 16. They are on a set of 16 X 7 rims. I will let you know once I put them on how the car handles. If I don't like how they work I will put them on ebay.

 

Greg, If you have more then 75% of the rubber left trust me someone will buy them. You will probably get half the price back. I had 245 on the back of my car when I first got it and it anoid me just to look at it. Definately stick with the 1.15 rule. Oh and for anyone interested 235/55/16 on S wheels at normal ride height does not work so dont do it. I get a lot of driver side fender rub.