ASK ALL WHEEL/TIRE FITMENT QUESTIONS HERE - The Official Wheel/Tire Fitment Thread

[robspeed325i]

both centers are stamped rs 070 et 16...if that doesn't make sense how would i figure out the offset?

whats to figure out? it says it right there: ET16 (16mm offset)

[dannyg]

Both front and rear? That wouldn't make much sense. Double check that first.

? I know the lips have been changed, but would that effect offset? The backspacing has stayed the same...This offset stuff really confuses me...:curse:

[robspeed325i]

? I know the lips have been changed, but would that effect offset? The backspacing has stayed the same...This offset stuff really confuses me...:curse:

ahh sorry for butting in... they are multi-piece wheels!? yes if you change the lips the offset changes. offset is the difference between the centerline and the mounting surface. if you move the centerline (by changing the size of one of the lips), youve changed offset. measure the total width of the wheel, then the backspacing, then you do a lil math and get the offset. (width/2) - backspacing = offset. most of the time you get a negative number...


so if i have a 10" wide wheel, and it has backspacing of 5", then the offset is zero. half of 10 (5), minus 5 = zip. if its (backspacing) 5.5, then the offset is -.5 or about 12mm (negative, obviously)....

i *think* i have that right! ;)

[Gooch]

What tires would it take to fit 16x7.5 ET 12 fronts and 16x8.5 ET 21 rears on a five lug swapped e30? Or would they fit correctly? The tires are 205/55/R16 fronts and 225/50/16 (which I'm assuming WON'T fit, but correct me if I'm wrong.)

Thanks, guys.

[dannyg]

Here are the pics:

On the rears from edge to edge I almost get 8.5 inches.



From tire bead to bead I get 7.5 inches.



On the fronts from edge to edge I almost get 8 inches.



From tire bead to tire bead I get 7 inches.



Here is what the centers are stamped with:



Safe to say that the fronts haven't had the offset change, because from bead to bead its still 7 inches wide and the centers are marked 7x15 et16? Now what about the rears? Would this be right, 4.25 centerline with 5 backspacing = -.75 = -19mm rear et?

[robspeed325i]

i get 3.75 as your centerline (you measure from inside lip to inside lip) so your formula is 3.75-5" = 1.25" or about 32mm (31.75mm) negative offset...

[dannyg]

So I have et16 in the front and et32 in the rear? is that correct?

[robspeed325i]

yep

So I have et16 in the front and et32 in the rear? is that correct?

looks that way. somebody correct me if im wrong! :)

[dannyg]

I think the backspacing is 4.15 because if the fronts are 16 mm or .65 inches, and my centerline is 3.5 on the fronts, the backspacing has to be 4.15. And if I use the same backspacing for the rears I get 3.75 - 4.15 = -0.4 or 10 mm...is this right?

[Mystikal]

I just got 215/40s on my 16x8 wheels running H&R sport springs. I put the fronts on and put it on the ground and the tire height seems really small. I'm thinking about going with a lower suspension soon so would it be a bad idea to pay for some 215/45s?

It's not just you, 215/40 is tiny. It can really only be pulled off on LOW cars.

The decision is yours. Not my money. :p

[Mystikal]

Here are the pics:

On the rears from edge to edge I almost get 8.5 inches.



From tire bead to bead I get 7.5 inches.



On the fronts from edge to edge I almost get 8 inches.



From tire bead to tire bead I get 7 inches.



Here is what the centers are stamped with:



Safe to say that the fronts haven't had the offset change, because from bead to bead its still 7 inches wide and the centers are marked 7x15 et16? Now what about the rears? Would this be right, 4.25 centerline with 5 backspacing = -.75 = -19mm rear et?

Ah, 070's...those are some rare RS', one of the few that came stock with 1.5" lips.

Those are 15x7 ET16 fronts (those are stock lips) and 15x7.5 ET10 rears. You had the right idea measuring from the tire bead sections, this is where it matters. So, 1.5" front lips and 2.0" rear. Not bad at all, and good for an E30.

You can do 205/50/15 if you roll the rear fenders well. 195/55/15 will be easier (still need to roll, but a little less aggressively).

[Mystikal]

they currently wear 195/50 falken ziex 512s. they barely (HEHE!) fit my 02 (using 8mm spacers), and they are destined for e30 after spring melt. :)



here they are on the 02:

For an E30, they'd need the 8mm spacers too. Even with them, they come pretty close to the struts in the front. Of course, something like a 205/55 would be a better size for the E30.

[Mystikal]

What tires would it take to fit 16x7.5 ET 12 fronts and 16x8.5 ET 21 rears on a five lug swapped e30? Or would they fit correctly? The tires are 205/55/R16 fronts and 225/50/16 (which I'm assuming WON'T fit, but correct me if I'm wrong.)

Thanks, guys.

Cool sizes.

I'd recommend 205/45/16 front and 215/40/16 rear. This will work with a mild fender roll in the back.

205/50/16 front and 225/45/16 rear would be even cooler, but you'd definitely need to spend some more time with a heat gun and roller. It'd look great though.

[dannyg]

jay should I run the same sizes front and rear? What if I want the stretched look so my lips will stick out?

[netcsk]

I've got a quick one for you:
I'm currently running 15x7 Kosei's with 225/50s
Thinking of going to 16x7.5 et 20
My car is not slammed (only M3 springs) and I don't plan on making it much lower in the near future.
What tire size do you recommend for me? This sound like the correct offset?
Also, if you have a good tire choice for a mostly DD, I'd appreciate it (with some aggressive driving -- my last tires with BF Goodrich Gforce sports and I liked them). If not, no problem.

I really appreciate it bud.