17's or 18's

[cleard8]

which one hooks up better with a street radial?

[thedak]

Word

[MuhThugga]

17s due to having more sidewall

But the softness of the sidewall is important, too. The stiffer the sidewall, the less traction.

[Chilly Palmer]

The stiffness of the tires sidewall is just as big a factor as the wheel diameter, when talking straightline traction.