I've got a Touring with the stock rims and tires at the moment. The rims are OK, but not exactly thrilling me and so I've decided to replace them and upgrade tires at the same time. My bias in all this is to balance performance and looks 50/50. I hate multispoke and chrome rims, generally preferring 5 and 6 spoke silver finish designs.

After upsizing my rims twice on my old Zs I learned the hard way the negative impact on accelaration and transient response of adding more rotating metal at the corners - so I'm not interested in going up to 19" wheels or larger. At the same time I'm sensitive to looks so I don't want to go down to 17s either - or buy wheels strictly on the basis of their weight. I dont really like the looks of any of the racing style low weight rims I see. But I would like to get something lighter than the Touring rims but which still looks better than average on the car (to me). All of that leads me to the Track rims. They look quite good if not beautiful, match the looks of the car and weigh a LOT less the touring rims so I'm thinking that's the way to go.

My predisposition on tires is to go with S03s as they were great on my old twin turbo. But that then leads to tire sizes. I'm curious about peoples opinions on sizes vs. performance vs. the inherent understeer in the car. Obviously I can just buy S03s in 225-45-18s and 245-45-18s and be done with it. It might be interesting to get a little more rubber on the road though. The problem with the 45-18s is the limited number of widths available. It looks to me the only way to go to anything wider I'd have to drop down to 40-18s where combinations like 255-40-18 front and 275-40-18 rear become possible. A little smaller diameter overall than ideal, but I suspect close enough not to cause any major problems. Heck if anything, the smaller rear diameter might even help off the line performance a miniscule amount.

My question to anyone with tire set-up experience and familiartiy with the degree of understeer thais car has does this sort of set up make sense? Or am I better off pushing towards 245s or 255s both front and rear? I don't want to push into serious oversteer territory, but a better balance would be nice while lowering the weight of the current wheel /tire combo.

Any thoughts or other recommendations I should consider?
Thanks!

Joe

 

in the mega thread tires and wheels, some Jeff talked to some wheel engineer guys who did testing and found the BEST combo to be 18x8.5 with 245/40 and 18x10" with 275/35 rubber.

My problem with this is he 35 on the back...is that right?

And Jeff also metioned that both should have a 38 mm offset. Arent the fronts supposed to have less offset? and wouldnt 32mm look better as they would stick out more.

...obviously I dont have the answers sorry!

 

If anyone figures out the right upsize on 18's, I'd love to hear it.

 

I may have an interst in your rims, PM me

 

255/40-18 IS the right upsize for the stock rims. 245/40 on the front. The 255/40 will theoretically and ever so slightly improve acceleration. But only a very small unnoticeable amount. Want to cure under steer, do what I did and add a heavy subwoofer to the back

 

I take that back for the rear tires....this is not good. the best you can hope for is 275/40 but this will impact acceleration. You cannot go to 275 and stay "correct." YOU WILL HAVE TO DEAL WITH ERROR if you go that wide.

My post above is the best bet!!!!