Tire compound vs Tire size
 

For track day purpose, i have a set of Yokoham AD08r in 205/55/R16 size and a set of CSC5 in 225/45/R17 size.

I know the Yoko compound offers better grip vs the contis. But the contis have a larger footprint.

Which one will offer more outright grip for track use?

Depends on alignment, weight of the car, etc. A stock weight FRS/BRZ is probably a bit heavy for the 205's though.

Hmm, even if 205 is stock width in markets with 16" for lesser trims?

205 is stock for certain Asia markets. Actually the car is so nimble on 205, grip is low which makes driving in certain conditions tricky.

Assuming all factors constant, weight, alignment, etc, am still trying to figure out which one provides more grip, not necessarily lap times

aside from the rubber compound/stickiness, the ~10mm difference in sidewall might be something you want to take in consideration too for turn ins.

Well, strangely enough i have answered my own question with a run at the track.

1st Run: AD08R, 205/55/R16
2nd Run: CSC5, 225/45/R17

Conditions on the day was basically identical, the suspension setup, camber, caster, etc all identical on both runs. Only difference was the weight of the tire/rim combo and of course, the tire itself.

Long story short, compound wins!
AD08R, even though less wide, gave better grip in all corners, i could corner harder w/o breaking traction.

Now i won't talk about lap times cos i am not a pro-racer and they aren't always consistent across the board, i am still slowly improving, but having said that, i did better in the 2nd run with regards to cornering lines, confidence, braking points etc, but my 1st run lap times were still lower!

End of thread!