stingraymax

I'm looking to replace my wheels by some 17 wheels.
Now I was looking at TT 17x8 with 4"Backspace, now the backspacing should be ok but now they have a offset of -11mm.

If I look at other wheels I see the 17x8 4"bs and 0 offset.

I searched the forum but find lot's of posts for the Back spacing but not for the offset.

Can somebody tell me what offset I need or can max get so the wheels/tires will fit under my stock wheel wells .
It's for a '75 with stock trailing arms and I'm goin to install t a VBP 360 composit spring.

Thanks

gkull

The center part of the wheel is where you measure back spacing. Our c-3 calipers hang outboard of the axle wheel stud mating surface. So you have to buy wheels with caliper clearance.

tire widths require a certain rim size. You really need 9 inch to use 255/45/17.

I have front 9 inch with 4 inch bs and 4.5 bs rear 12 inch

zwede

What's confusing you is that an 8" rim with 4" BS does not have 0 mm offset. The reason is that 8" is the width of the inner part of the rim where the tire is. BS is measured from the outside of the lip. 11 mm is the thickness of the lip.

So 17x8 with 4" BS is correct. If someone says they have an 8" rim with 4" BS and 0 offset they are mistaken.

Robert Thomas

My Vette has 17x8, 4" BS wheels with 255-17/45 BFG Comp 2s on the front and back with no problems.
4" BS on 8" rims is 0 offset.
As far as 8" wheels being too narrow for 255 tires, my car's stock wheels are 8" wide and came with 255 tires. My new tires' specs show 8-9.5" wheels.

stingraymax

OK thanks for the info, so TTII 17x8 with 4" BS and -11mm offset would fit under the car without a problem.

Would the same wheel with 4.5BS and 0 offset fit the same ?

69autoXr

No, it would sit 0.5" deeper in the wheel well and you'd lose 1" of track width overall. The 0.5" is very noticeable.

gkull

I did not explain it very well. Maybe this will help. As to 8 inch wheels they are the minimum and the tire side walls would slope in because the tire tread width is wider. So the tire is not being used to its potential. Smarter people use the correct rim widths.

stingraymax

Thanks for the help, I believe I got it now ;-)

I was planning on going with 245/55 - 17

zwede

On the plus side, if you scrape a curb you'll scuff the tire instead of destroying the rim. On my other car the rim will hit before the tire and I'm scared to death to parallel park the thing.

It would look very goofy and with a 255 tire it will hit the frame at full lock. Stick to 4" BS on a 8" rim.

Barry's70LT1

If you want the "original" look, these look interesting. They have a 4.5" BS, so a 1/2" spacer would be required.
https://www.yearone.com/Catalog/whee...-wheels-.-cast

69autoXr

"Corvette Rally Wheels" and they don't even offer them with the correct backspace for a Corvette? Seems kind of lame to me.

scottyp99

"kind of"??? You're being generous. It's WAY lame!

Scott

ddawson

stingraymax

I found this site which makes it very easy to check the sizes

http://www.rimsntires.com/specspro.jsp

scottyp99

The shorter the sidewall becomes, the more crucial it is to have the tread width match the wheel width, for reasons that are fairly obvious once you give some thought.

Scott

Robert Thomas

Yep, I was incorrect. The wheels are -11 mm offset.

Robert Thomas

And, not being smart, when I want to use all of the traction I switch to 17×9.5 wheels with 275/45-17 race tires (same size my '93 C4 came with). I don't like chewing up the street tires, not being smart and all.

gkull

So you recommend 8X17 wheels

zwede

17x8 rims are perfectly fine on the street. Or are you saying we should pretend our city streets are a race track?

jb78L-82

I have had SLP Hyperblack C4 ZR-1 type rims for years on my C3-17 X8-255/45/17 ZR's-fit perfectly. I stole them from MidAmerica on closeout for $600 for 4 with free shipping! Could not take the C3 aluminum 15 inch rims any longer with zero performance tire in the 15 inch size. One of the best changes i have ever made to the car!