tires

[MMarty]

Hey all, I am building a 71 olds cutlass for some occasional road racing, my plans are eibach springs(front and rear),sc&c upper A arms QA1 shocks all around and tubular lower rear control arms. My question would I get the same benefit running 15 inch rims with 50 series performance tires as I would running 17 inch rims with 40 or 45 series tires. I won't be hard core corner carving (mostly street) but I would like to enter some road course events. Thanks.

[6'9"Witha69]

the stiffer sidewall of the 17's give it the advantage never mind the selection for performance tires is maasive in 17"+ compared to 15"s paltry selection.

[fast Ed]

From my 72 Cutlass experience about 25 years ago, 15" wheels would need at least 60-series rubber to fill up the huge fender openings. As mentioned, there is very little available in large car 15" real performance tires these days (Radial T/As don't count).

IMO you would be better off with at least 16" wheels, and 255/50/16 rubber (which is still fairly available), or go up to 17" as suggested by Nick. 255/50/17 would probably be a nice fit on the car, enough width to get the job done, and enough height to fill up the wheelwells. I recall having 255/60/15 and 265/60/15 on mine back in the day, with no clearance issues.


cheers
Ed N.