Jerome104

18" wheels seem to be the preferred choice for the track. Is it because it provides quicker acceleration given shorter radius? What else?

tcsracing1

18" tires are cheaper then 19" tires.
18" also offer a lot of available sizes in both R compound tires and slicks.

kosmo

Cost and selection are primary reasons.

Slight weight savings is secondary.

TRAKCAR

18" OZ or BBS let's you run 18" NT01 and my cheap RA1 but RS size only. $900 a set, I do think 18" might ales be a bit better on rumbles and bumpy tracks.

ShakeNBake

hoosier r6 seems to slide more on rim on 19s than on 18s.

Izzone

Hoosier are not load rated for gt3,

Use 18 nitto

kosmo

what do you mean shorter radius? wouldnt the overall size be constant? Less wheel but more sidewall?

ShakeNBake

The overall diameter is about 1" shorter with 18" wheels.

dasams

Correct but the wheel is much more dense than the tire and it's possible the 18" has a lower moment of inertia. Nonetheless, the real reason is tire selection as noted above.

ShakeNBake

For example:

335/30/18 is 25.6" diameter (the correct size)
335/30/19 is 26.8"
The front/rear ratio is all the really matters, and you can get very close to stock in both 18 and 19 R6s (and a lot of other tires in 18").

kosmo

yes, usually i increase the aspect ratio when going down in wheel size in order to keep the diameter constant.

ShakeNBake

you can't in this case - the tires in a higher aspect ratio don't exist.

mdrums

Yep the overal size ratio we use for 18" is about the same as stock 19". 18" just performs better and the slightly taller side wall flexes a little more and helps with corner traction. Plus like everyone else says there is a better selection of 18" r comp tires than 19".

tgsmith4845

I use 18" w/ Nitto NT01s on the track. I like the tire selections the 18" offers. 19" on the street.

Red Bear

One vote for 19's set up with R6's as I prefer the gearing on high HP tracks.