ive found questions dont get answered here as fast as on the detailing board... ive searched my butt off and thats how ive done all this math but of course since every car is different i need help/opinions. ive emailed severall wheel companys (tire rack etc) and recieved no response...id appreciate it if some1 could take the time to give a little help/advise.


ive got my backspacing figured out but i need some 2nd opinions if this will fit, try and follow me here.

my rims are 8.5 and 9.5 inches wide and for backspacing purposes respectivly (approx.) 9.5 and 10.5 inches wide couting the edge of the wheel outside the bead. with a zero offset i get 4.75 and 5.25 BS for them.
they do have a +35mm offset (all 4 wheels) which gives me a BS of 6.13 and 6.63 inches.
however, i have 1 1/4" (actually measured out to 1 5/16") spacers and putting those on would return my BS to 4.88 in the front and 5.38 in the rear. is this math correct?

now i do have the c4/1le brakes in the front that moves the front wheels out another 1/4" (approx) but i dont think this will play a major role.

for reference i have 7.5" wheels now on all 4 corners with 4.5" BS and they fit just right to be tucked even more so...

i know its close but can i get away with approx 4.88 BS in the front with a 8.5" wide wheel and approx 5.38 BS in the rear with a 9.5" wide wheel???

TIA

 

pics always help posts

 

4.88 might be a little tight in the front. - would depend on what diameter wheels you plan on running(struts at inward angle=more backspace available for larger wheels). Take a piece of metal(preferably angle) cut to the width of wheel you want to run. Then drill holes to moun onto 2 of your wheel studs. Then drill a whole at the end(@ intended wheel radius) and run a piece of all-thread(threaded rod) in w/ a nut on either side of the piece of metal. you can now run the rod in/out and measure your backspace. Rotate/turn wheels to make sure you won't come into contact w/ anything. - Thats the best way to check, for as you said, everycar is different(ride height, brakes, bumpstops, etc...)

 

thakns for the time/help shagwell. i do need to get some measurements but at the present time there isnt anything to measure! and the ETA of this build keeps slipping away

the wheels i did these calculations on though are 19" so that should give me some leeway (with the struts)

 

First, you're correct in using the outside-to-outside measurement here. Second, don't worry about backspace from a 0 offset, just cut the outside-to-outside in half to establish your centerline:
front: 4.75" centerline (1/2 of 9.5" wide)
rear: 5.25" centerline (1/2 of 10.5" wide)

+35mm = 1.38" (1" = 25.4mm), so you just add the +offset to the centerline to get the backspace.
front: 4.75" centerline + 1.38" offset = 6.13" backspace
rear: 5.25" centerline + 1.38" offset = 6.63" backspace

1 5/16" = 1.31"

Subtract the width of the spacers from the backspace to arrive at the backspace with the spacers installed.

Front: 6.13" backspace - 1.31" spacer width = 4.82" effective backspace.
Rear: 6.63" backspace - 1.31" spacer width = 5.32" effective backspace.

The only way to be sure is to put them on the car and see if they fit. These calculations can only get you so close.

 

There's a great tool you can use to "test fit" these wheels to your car, even if you don't have them. It's called a Mount Mate. You put the tire you want to run on it, then bolt it on the car. You can simulate any backspace you like.

http://www.autowaretech7.net/mmhow.html

If you call those guys, they can tell you if anyone in your area has one.

 

yea thats nice. would be a worth while investement, i think ill call them this week.

the reason i ask to check my measurements is because basically i want to know if i can possibly run the 4.82" BS on the front and the 5.32" BS on the rear or if it is a total NO GO. i dont even know what i can get away with on this car and the car is dissassembled so no measurements can be taken.

 

I'm sure you could run 5.32 on the back, and w/ a 19" you could probably get buy w/ 4.82 on the front. I'm running 4.25 on the front, and I should have gone 4.5(maybe it was 4.0/4.25...)They don't stick out past the top lip, but they could be tucked a little more. Thats w/ 17's, so a 19 would get you further away from the strut. I'm gonna move my front track width in aprrox 1/4-1/2 on each side w/ the new frame. - I'm switching to a full frame, and cutting out ALL the unibody structure. stinkin' 4161lb land barge...

p.s. I'm running an 8" offset rear, but I've got a 4th gen rear...

 

nice

well i got a response finally from a company that sells these and they said i would need 1 1/2" spacers. mine are 1 1/4" but i do have the C4 brakes up front that would goive me about 1/4" so im hoping the rears will work out. think i should go with it?

 

If you like the wheels, go with it. If the spacers don't work, you can buy new ones and defray the cost by selling the old ones on here or on ebay. Don't let something as trivial as wheel spacers stop you from having the wheels you really want.

 

1-1/4 wheel spacers, plus 1/4 extra for brakes...should be your 1-1/2 needed in the front...as for the rear, you can easily pick up the extra 1/4 with a BFH...

 

i do really want these wheels and after i paint them i think they will be perfect. i dont mind running spacers and i guess this should work just fine.

now i just need to get some 19" tires