I have 40 series on my 17's up front and have never damaged them yet. The roads here in California are the as bad as I have seen in any state. If you go with 18s you are probably looking at a 35 series to get the same overall height as stock if you go with a 245 or 255. I have seen some cars with 275s in front, but you'd have to go 30 series then.
Basically, a deep pothole hit at highway speed could damage a rim, but you are not going to hurt anything just driving normally on really bumpy roads.
__________________
Strike down the unroadworthy!
2000 GT Atl. Blue: '03 Cobra motor - 465rwhp/473rwtq, T-56 6-speed, full MM TA/PH & tubular K-member suspension, Saleen body, 17" Torq-Thrust II's, M/T ET Street radials, and lots more
'94 Rio Red Cobra: All the bolt-ons, 3.73s
|