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So picked up some BBS E88 wheels that I think were off a cup car
The rears are 18 x 12 with a backspace measure of around 7 3/4"
So does that equate to a 44.45 mm offset? Is that in line to what I can run - it looks like it could fit with a little messaging of the wheels well lines
The fronts don't look as close - they are 18 x 10 with a 6.5" backspace (so 38.5 mm offset?)
They look like they stick out way to much from the fenders - even with a health degree of camber .
I have a set of Pss9's I plan on putting on - so don't have to worry about the giant OEM spring carriers
What do I need to run these? here are some pictures
If you are trying to equate backspace with offset, you need to account for the distance from the tire bead to the inner lip. Generally, the distance from tire bead to lip is around 1/2" so for a 12" wide wheel it's approximately 6.5" to wheel centerline.
If my approximations are correct in your case, a rear wheel with 7.75" backspace would be approximately a 32mm offset: (7.75"-6.5")x25.4
While your fronts would be about 25mm offset: (6.5"-5.5")x25.4
You'll need to measure the bead to lip distance and do the calculation above to be more accurate. But in summary, if I'm close, you're going to have some problems trying to fit these.
The Bead to the outside of the rim is approximately .5" or 1cm
Wheel center backspacing is 6 5/8th inches or 17 cm
So around 30-31mm offset
Originally Posted by g-50cab
Rear - outside to outside is 12 7/8 " or 32.6 cm again the bead to the outside of the rim is approximately .5" or 1 cm
Wheel backspacing on the rear is 8 3/16" or 20.8 cm
So around 44-45mm offset
So your rear is looking pretty good, while front is going to be a problem. Might be possible to only change the outer rim half to turn it into a 9" wide wheel with around a 43mm offset.
Post up the serial number that is stamped into the face of each wheel center and the width of the inner and outer barrels (listed on the sticker on each rim half). I will tell you exactly what offsets you have. No guess work.
Bottom line, you will not be able to run 18x10s with stock suspension components or PSS10s.. It can be done but it requires a full race suspension with very specific components, setting and modifications. To run these as a direct bolt on, on the fronts you will want a 1/8 or 1.5/7.5 combo (depending on which center you have) to give you a 9" wheel. I suspect your front center is a 274 as that is what is required to clear 380Cup brakes. Widebody rear 12" wheel will typically run a 3.5/8.5 barrels giving you a 44 offset. Cup cars will typically use a 2.5/9.5 barrels as they run shallower offsets but a lot depends on the center used.
Last edited by powdrhound; 10-21-2017 at 01:44 AM.
So both the front and rear centers are 288170? If that's the case than you have:
18x10 ET 30.8 (2/8)
18x12 ET 43.5 (2.5/9.5)
You could swap the front 2" outer barrel to 1" and have an 18x9 ET 43.5 (1/8) front for a plug and play set up. The 170 centers are 997Cup center lock centers that have been drilled out for 5 lug use.
Last edited by powdrhound; 10-20-2017 at 10:36 PM.
Email Bob Woodman or BBS Motorsports USA with your center part number and outer and inner barrel measurements. They will tell you what offsets you have and what it will take to get to the offset you need.
Email Bob Woodman or BBS Motorsports USA with your center part number and outer and inner barrel measurements. They will tell you what offsets you have and what it will take to get to the offset you need.
Pretty sure John just did that for him in the post above...OP listen to powdrhound
So both the front and rear centers are 288170? If that's the case than you have:
18x10 ET 30.8 (2/8)
18x12 ET 43.5 (2.5/9.5)
You could swap the front 2" outer barrel to 1" and have an 18x9 ET 43.5 (1/8) front for a plug and play set up. The 170 centers are 997Cup center lock centers that have been drilled out for 5 lug use.
Thank you Thank you
So I can run the 18 x 12 rears? Looks like it's tight against the fender liner - and that's without a tire...
So I can run the 18 x 12 rears? Looks like it's tight against the fender liner - and that's without a tire...
I run 12” rear e88 with no problem. Offset is +42 and it requires the gt2 fender liner bracket. The 1/2” it gives you makes all the difference for clearance. Good luck.
10-20-2017, 04:49 PM
A little help with some BBS wheels and offsets
