backspacing?

[[email protected]]

ok Iam getting a conflict of interest here! which pic is the correct way to measure backspacing?

[6spdcamaro]

Second one :2nd:

[68/CamaroFL]

BirdBoy that would be the second pic you have here is another pic for you for Backspacing

https://static1.pt-content.com/images/pt/2010/10/Offset5-1.jpg

[Wicked]

Definitely the second pic. Also consider the tire bulge when sizing your wheels.

[DarkBuddha]

The second is correct for measuring backspacing, but the first one could be used to calculate offset (assuming you knew the advertised wheel width). It seems a lot of folks obsess over offset these days when it is in fact the backspacing that is the important thing to know.

[[email protected]]

Thanks so much guys. I have a friend that has been in the tire business and he swore the first pic was the right way. Ill go with what you guys say and let him know. Thanks again!:cheers:

[elitecustombody]

your friend is wrong, ask him how many times he had people with wheel fitment issues after his calculations.

[[email protected]]

He was quick to agree with what you guys said. He obviously got the wrong info from someone else. I always ask for several opinions..you know everyone has one, but are not always the right one. I feel confident that u guys know your stuff. Thanks again.:jump:

[Lex]

Hi. Does the wheel fitment change when you change drum brakes to disc brakes?

[Taman]

Yes and no. Depends on how big a disc brake and the shape and size of the inside of the rim. My stock 15" Ralley 2 wheels do not fit over my rear 12.19" rear disc with 4 piston calipers. My 15" nascar sytle steel wheel with my slicks on will fit.

[mc84_zz4]

So what's the big deal being off by 1/4" inch, right? ... lol
:machine:

[Lex]

Thanks Taman

[cheapthrillz]

Yes and no. Depends on how big a disc brake and the shape and size of the inside of the rim. My stock 15" Ralley 2 wheels do not fit over my rear 12.19" rear disc with 4 piston calipers. My 15" nascar sytle steel wheel with my slicks on will fit.

I think Lex is referring to track width changes when converting from drums to discs?

If so, then yes, it could change it enough to cause some scrub issues if you are already running a wide wheel.... this is assuming that we are concentrating on backspacing (the original subject of this thread).

[Taman]

On rear brakes the disc is not much thicker than the drum.Maybe .050". Both mount flush to the axle flange so track width is not as affected as in the front wheels. What does change is where the caliper mounts. That can force one to run a different back space.

[elitecustombody]

So what's the big deal being off by 1/4" inch, right? ... lol
:machine:

sometimes 1/4" free space is all there is to work with

[dhutton]

Don't you have to deduct a half inch for the lip in the second picture to get backspacing? My memory is a little rusty but I think that is the case. For example, I think a 10 inch rim actually measures 11 inches lip to lip, doesn't it?

[JustinB]

Second picture is right. If you need help figuring out the BS, feel free to give Jon or myself a call.

[strtlegal]

Don't you have to deduct a half inch for the lip in the second picture to get backspacing? My memory is a little rusty but I think that is the case. For example, I think a 10 inch rim actually measures 11 inches lip to lip, doesn't it?

That's always been the case with rims I've messed with. It does seam however some manufactures are different, Including there backspacing measurement..The second piCture in a perfect world would be correct, but I dont think everyone supports it. Meaning I've measureD Budnik's and A/R and they seam to have a different back spacing then ordered until I measured inside the lip. Others are on the outside...

Looking at the first picture the angle rod seams to be the same thickness as the rim lip so measuring it would pretty much yield the same measurement as the second picture...

I do agree the second picture should be the right way

[JustinB]

The second pic is the industry standard and the only correct way to measure backspace.



That's always been the case with rims I've messed with. It does seam however some manufactures are different, Including there backspacing measurement..The second piCture in a perfect world would be correct, but I dont think everyone supports it. Meaning I've measureD Budnik's and A/R and they seam to have a different back spacing then ordered until I measured inside the lip. Others are on the outside...

Looking at the first picture the angle rod seams to be the same thickness as the rim lip so measuring it would pretty much yield the same measurement as the second picture...

I do agree the second picture should be the right way

[dhutton]

The second pic is the industry standard and the only correct way to measure backspace.

So you are saying you do not have to deduct 1/2 inch for the lip?

Thanks.

[JustinB]

So you are saying you do not have to deduct 1/2 inch for the lip?

Thanks.

Exactly. You lay a straight edge across the back of the wheel and measure down to the back side of the pad. That's it.

[dhutton]

Exactly. You lay a straight edge across the back of the wheel and measure down to the back side of the pad. That's it.

Thanks for setting me straight.