Re: how wide of tire on 18x9.5 rim?
Yep, check the manufacturer's spec. They will give the acceptable wheel widths for a given tire size, and they also list the wheel size the tire was mounted on when it was measured for section width.
If the spec lists 9.0-(10.0)-11.0 that means 9" is the minimum acceptable wheel width, 10.0" was the wheel that the tire was mounted on to take the section width & diameter measurement, and 11.0" is the maximum wheel width.
Mounting the tire on a wheel that is out of spec range will stress the sidewall beyond the manufacturer's tested and approved limits... you may have problems, you may not. Also remember that as you mount a tire on a narrower wheel you decrease the actual contact patch and the tire will have more "squirmy" and unstable sidewalls, and as you mount the tire on a wider wheel the contact patch increases and the sidewalls stiffen up.
The Nitto 305/45/18 you mentioned is rated from 9.5 to 11.5 per Nitto's spec sheet, so it would be OK to mount. Keep in mind that's almost a 29" tall tire though!
Old setup: Procharged/intercooled/EFI 353 SBC, TKO, ATS/SPC/Global West suspension, C6 brakes & hydroboost.
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Last edited by Gokou; Jul 1st, 08 at 1:45 PM.