GettReal

One of my track wheel sets are 18x10.5 and 19x9.5 that currently have hoosiers on them, but they are at the end of their day.

I have 2 full sets (8 tires) of Pirelli Grand Am slicks that are 305/660/18.

Is 305 too wide for a 9.5 for track use?? Yes I know that its too big by manufacturer specs but should be able to get them on ok, anyone else run sizes like this??

Hoosiers max for a 9.5 wheel is 295 so not like its too far off, and Kumho's 305's suggest a 10.5"

Sidney004

The 305's should be fine on the 10.5's. I think the 9.5's may be too skinny for a 305 but I have no direct experience.

GettReal

Need to mount these, any other comments? experience?

trackboss

I had those same tires on 12" wheels. For the front I had the 285/645 on 11" wheels. I would think the 305 are ok (not ideal) on 10.5 wheels. Any narrower and I wouldn't try it.
Whatever you do, keep in mind those tires will have near zero grip until you get some serious heat in them. Slowly build heat into them over 3+ laps or you might find yourself off the track somewhere or worse. Once you get them to stick they are excellent. I ran some tt with them and they were a huge disadvantage because of the traffic. All the guys on hoosier A's simply ran hard out of the whole and got in their good laps very early. Not an ideal tire for ripping off a single fast qualifying type lap unless you have tire warmers and the support needed to use them properly.