Author Topic: Please Help Question Re:- backspace (Read 6943 times)

mick · « **on:** January 13, 2006, 07:19:48 AM »

Hi all,
Im just organising ordering my wheels for my vet and the guy got back to me with backspace specs. see below

15x8 with 3 ¾” BS

15x10 with 3 ¾ BS

17x8 with 4 ¾ BS

17x9.5 with 6 ½ BS

I was seriously considering the 17 inch wheels because of how much better the car will handle (im told). But why such wierd backspace numbers it just seems wrong and I am worried to order these wheels if the backspace is incorrect.

Thanks

Mick

vette2bshaw · « **Reply #1 on:** January 13, 2006, 08:26:07 AM »

With the back space on the 15s I think the diamiter on the inside would rub on your rear spring or your front rod end, But with the 17s the diametre being bigger they can be set in deeper because the rod end and rear spring would sit within the rim and not interfear,

vette2bshaw · « **Reply #2 on:** January 13, 2006, 08:32:40 AM »

The only thing with the 17 rear if you decide to lower the rear by extending the rod at each end of the spring you start getting close to the inside diametre,

mick · « **Reply #3 on:** January 13, 2006, 09:50:07 AM »

thanks for your info that help make my decision to get 15's cause i will eventually lower the car.

69 DIRTY RAT · « **Reply #4 on:** January 13, 2006, 10:41:43 AM »

Quote

Originally posted by mick
Hi all,
Im just organising ordering my wheels for my vet and the guy got back to me with backspace specs. see below

15x8 with 3 ¾” BS

15x10 with 3 ¾ BS

17x8 with 4 ¾ BS

17x9.5 with 6 ½ BS

I was seriously considering the 17 inch wheels because of how much better the car will handle (im told). But why such wierd backspace numbers it just seems wrong and I am worried to order these wheels if the backspace is incorrect.

Thanks

Mick

the 17in specs dont sound right!!! my front are 4inch(Ithink?) & my back are 5inch backspace....thats with 18x10 front 18x12 back! (with flares &offset trailarms) SO if anything, it should be less than mine? 6 1/2 in I think will definately hit?
If you dont have offset trailarms your back space should be the same as any rallye wheel!

mick · « **Reply #5 on:** January 13, 2006, 12:11:05 PM »

Ive decided on 15's for sure now. There On Order.

Thanks Guys

vette2bshaw · « **Reply #6 on:** January 13, 2006, 04:39:54 PM »

If it not to late I hope you took into acount caliper clearence ,The corvette 4spots exceed the stud face of your disc by about 10mm and if you buy rims that are too flat in side such as weld and some others ,you then have to use spacer with extended studs (not good for high torque engines and not truely leagle) or spend a lot on new disc and caliper modifications.

mick · « **Reply #7 on:** January 13, 2006, 07:31:08 PM »

I spoke to someone who already has these wheel's and he assured me that at the above back spacing for the 15's anyway all is good. Thanks for asking but it would have been an expensive fix if they didnt fit right.

77CVT · « **Reply #8 on:** January 13, 2006, 11:35:15 PM »

old thread

For an 8 inch rim you need a 4 -4 1/2 offset.

With a 10 inch rim you are limited by the trailing arms and the handbrake bracket (which you can move to the top of the arm). So the outside rim will move further to the outside of the car.

MADVET · « **Reply #9 on:** January 14, 2006, 08:48:25 PM »

3 3/4" back space isn't a lot. You will have quite a bit of "dish". Hopefully your flairs should cover them.

BTW back space and offset are two different things;
Back space is the distance between the mounting face and the outside edge of the inside rim.
Offset is the distance between the mounting face and the centre line of the wheel;-)