For no better reason than I'm insanely cheap, I'm running 15" wheels up front and 16" wheels in the back of my '88 924S. Tires match, but the back, of course, are wider.

From a handling perspective, is that an awful idea?

 

If the rolling diameters of the tires are similar, then it's not as great of a deal. There are cars and motorcycles that have used different wheel sizes front to rear without ill effect.

 

Not the best idea, as said before, the rolling diameter is the key for at least reasonable handling and speedometer accuracy. That being said, the 15's up front will most likely have a more compliant (cushier) ride since they will probably have taller sidewalls.

I'm not aware of any manufacturers that put different rim diameters on normal production cars, but certainly there have been many instances of different rim widths front to back.

 

It's fine... as other's said the Diameters are probably very close...

and lots of people run wider tires in the rear!

Hell i'm running 17"s all around that are 205 in the Front, and 255 in the Rear!! Ha ha <-- For no other reason then I bought the wheels with these tires, and I am too cheap to buy new tires...

 

I run it on my need for speed cars all the time. Its legit.

 

iirc corvettes have been doing this for awhile

 

Yes they have Doug, you're right. I know that most of the wheels i've seen for c6's for sale etc were 19's in the rear and 18's in the front.

to the OP, There's no problem running different size diameter wheels as long as you have the profiles matched properly front to rear. you can check to make sure everything is kosher here http://www.miata.net/garage/tirecalc.html

In some situations you should be able to get away with a little discrepancy front to rear in overall height of the tire...think about some of the combinations people run with 17's and 18's once you get into wider tires like 275 plus in the rear. The tire sizes become more limited when you're going that wide, and sometimes you have to run a tire that is just a tad short or tall to get the width that you want.

 

I believe the new Lotus Evora runs 19's in front and 20's in back. Or maybe it's 18/19's.

 

NSX did that too IIRC.

 

I don't think it will matter. It's not AWD. As long as the tires on the respective axle are the same size, shouldn't be a problem.

 

My buddy's 2000 Lotus Esprit has 17" wheels in the front and 18" wheels in the back... I don't think too many mullets are driving those...

 

Doesn't the Carrera GT run different diameters, too?

 

Seems like you would get even more understeer with a higher profile tire in front.

 

Thanks everyone. My diameters are pretty much spot on so I should be good. As for any extra understeer due to sidewall height, I'll let you know once I strap down my battery. Due to a rust issue (and therefore no strap) every time I take a spirited corner the battery will short out on the hood or pull loose... Guess I have more important things to worry about than tire setup at the moment.

 

pics?