supraman7mgte said:
I already have a set of 18X8.5's,and i don't know the offset. I will be using Nitto NT555's,245/40 ZR's up front,and 255/45's in the rear.
I want to go an inch wider in the rim size on back.
offset is almost always stamped on the wheel. also, offsets have ziltch to do with lip size. unless its a 3-piece. 1 piece wheels will have the same lip in any given dia./width. to get different offsets, they remove material from the hub flange.
245/40-18 is perfect for a 18-8.5" wheel, but your choice for the rear is all wrong. why would you switch to a 9.5" wheel and then put 255's on it?:3d_frown: also the overall diameter of a 255/45 is more than an inch bigger than the 245/40's in front. it will probably play havoc with your ABS if you still have it. i suggest 275/35-18 for the rear. much better suited to a 9.5" wheel and it would only be 0.1" difference in diameter from the front. although, even with this choice your stock speedometer will read 2.9% too slow. more of a nuicance than a problem.
as for, offsets... the offset is the measurement between the centerline of the wheel and the mounting surface. so if you change the width of the wheel, you also have to change the offset. for a 9.5" wheel in the rear, any offset between 37-51 "should" fit. 40ish should be close to flush with 0 camber but your car may be different so
its best to measure your own vehicle. you can go with a smaller offset by using narrower tires and/or running negative camber like blur. and of course, you can always roll the fender.