I've got a set of 3P Work Meister SP1's that I'm in the process of assembling and I'm needing to buy some tires. the problem is I've forgotten the offset for the wheels! the front is 18x8.5 (I think with around +40) and the rear is 18x9.5 (I think somewhere around the same offset). I am lowered 1.5" all around on AP1 stock.

Could anyone help me come up with the correct tire sizes to buy for max rubber:road and no rubbing ? Thanks!

 

Not without knowing the offset. There is no sticker or anything? You can measure it. Its the distance from the centerline of the wheel to the hub. Just going from your guesses you should be running a 225/40/18 up front and a 255/35/18 to keep the OEM rolling diameter.

 

I would consider 225/40, 255/35 ideal but that is going to require a fender roll and probably a decent amount of negative camber. If your fenders aren't rolled then there really isn't any tire size that would realistically work.

 

The offset is supposedly enough that I shouldn't need a fender roll, which I don't have.

 

You need an offset around +60 with those widths if you don't want to rub when lowered at all.

 

^this. Like I said measure the wheels and figure it out. Without that key measurement we are just guessing. Also if you are lowered even with OEM fitment you should roll the fenders.

 

+56 front +62 rear. He says he was running 225/40 front 255/35 rear.

 

Sounds good. Like I said you should still consider rolling the fenders because the fronts can still be a problem in the right circumstance.