Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, 245/45-17 on Stock '04 RIMS, Do they fit? in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; I wanted to upsize the stock 225/50-17's to 245/45-17's (same diameter, 20mm wider). The tire specs show sidewall to sidewall ...
I wanted to upsize the stock 225/50-17's to 245/45-17's (same diameter, 20mm wider). The tire specs show sidewall to sidewall is about 1/2 inch wider, so about a 1/4 inch more inside and out. The front steering knuckle is VERY close to the stock tire/wheel at the top. Has anyone fitted these tires to this combination yet? How close are they really going to end up?
A 245 tire is 20mm wider than a 225. That's 10mm on each side. If you stick your hand behind the top of the wheel, you'll see you have less than a finger's thickness of clearance (~10mm). It would be VERY close with the stock offset wheels (51mm ET). Most folks running 245's have switched to wheels running between 40 and 44mm offset. Stock V is 42mm.
I wouldn't do spacers, it loads the threads of the studs if there isn't enough hub engagement. You need at least 3 threads minimum as rule past any nut. The fender lips aren't the problem, the rim and tire are right up aginst the upper front steering knuckle with about 1/4" of clearance. Put your hand up behind the top of the tire and you'll see what I'm talking about. I really didn't want to go to a new rim and offset, but if I did, the 40mm would fill out the wheelwells nicely, then I'd need to choose a good +1 diameter like the 18's (or +2,+3).
Rules for aircraft is one full thread past the nut. Use the minimum spacer that will give you some clearance and you should be okay. If you are using crown nuts be sure you have 1 1/2 diameters of thread engagement minimum.