.38 per side do you mean 9/16 of an inch per side? from this conversion chart, that means the brakes push the wheel outward 9/16 of an inch per side and then you ran a rim thats .500 thousandths (or 1/2 wider offset than recommended) so 9/16 + 1/2

Find the lowest common denominator
* 1/2 by 8
= 8/16
Now you can add them both together since you have the same denominator
9/16 + 8/16 =
9+8 = 17
17/16 = 1 1/16

so your 1inch and a 1/16 too wide on your wheel and brake selection, on your car with the added brake dimension you stated I would have recommended about a 6.00 back space


lets use a 10 inch rim for example
5.25 back space would stick OUTWARD .500 thousands (1/2 inch) more than a 5.75 back space

http://i752.photobucket.com/albums/x...psd0c6cc67.jpg

hope this helps

AFAICT .38 of an inch per side is 38/100 per side or 76/100 total increase in width. Just over 3/4" (by .01") total.

Did I miss something?

a lot of time is spent testing what fits

this how basic back space is measured here, we lift the arm up to ride height and pick the tire width we would like to run
http://i752.photobucket.com/albums/x...ps908e8157.jpg

next we check for clearance at ball joints and steering arms
http://i752.photobucket.com/albums/x...ps9ca31251.jpg
http://i752.photobucket.com/albums/x...psfe05032d.jpg

and its simple after that it gives you the backspace, then we order a rims in that spacing bolt them on and drive, and we can shim the rim from there for final spacing
http://i752.photobucket.com/albums/x...ps0a5eb57f.jpg

SOMEONES been hanging out with Britt :lostmarbles:

Rod forgot to add that when checking for proper wheel fitment we stroke the suspension and turn the wheels to full lock. This makes sure we don't hit the finder at full compression, or the frame or sway bar at full lock in any situation.

It's simple to do. . .just remove the spring from the coil over, bolt the shock back in, and use a jack to stroke the suspension.

I STRONGLY suggest anyone trying to fit the largest wheel/tire under their car buy a GOOD measuring tool. The one in the pic is about $400. Sounds pricey, but what's Forgeline charge to change a wheel that doesn't fit your car?

yep you right True!! that damn chart was off :sarcasm_smiley:

some of the other things we spend time testing and fitting are spindles from other manufactures you can see in the picture here what we have on the shelf many to test from Heidts, DSE, ATS/speedtech, L&H and many others, testing for offsets, camber curves, bump steer among a few others things :thankyou:

http://i752.photobucket.com/albums/x...ps228b0b79.jpg

Bret or Josh,

Not intending to high jack a thread but I feel I'm covering a couple bases at once for others that have asked some of the same questions in other threads in the distant past .

First. Complements to you and your crew for this system. I am very happy with the engineering on this system. I went with the True Turn system and the Triple adj air bag coil overs. I have only installed the front so far and have done a couple test runs and I'm happy to report no rubbing after my mods to the inner fender. That is with 9.5s and 5.75 bs on a 69 Camaro with a big block.

Second. What is the suggested eye to eye for the front ( and rear) coil overs at ride height. I'm need that to mock up the Moser floater. I'm doing my own torque arm set up. I'm roughly 24" from floor to body line on front fender now.....with a big block at this time.

Third. On the 48 Hour Camaro, did you use Holleys newest engine mount system which places the motor over an inch from firewall? I can't get the Holley/Hooker guys to confirm anyone has used their newest system with the Ridetech True Turn system. Trying to find what will work.

Thanks,
David

Yeah your math was a little off but I think we are headed in the correct direction. Taking my brakes into account your are correct I should have ordered a 18x9 5.75 backspace but I went off what RideTech had posted on the website which was a 10 inch wide 5.75 backspace wheel would fit. There were no stipulations/recommendations around brake setup or anything like that and I really feel there should be. Even Brett stepped in earlier in the tread and stated the OP ordered the wrong wheels and should have ordered a 18x10 5.75 backspace without even looking at any other info. To he honest I am pretty disappointed with Ridetech and looking back I would have just gone with a aftermarket subframe. It least then I would have know exactly what fit and what didnt and I not be spending money doing the testing I feel Ridetech should have done before advertising their setup as a one stop shop.

Would love to see some pictures of the 69. what tire size did you use? What is the ride height?