Technical Wheel Offset For Dummies Like Me (Up Date)

Reading all the wording makes my head hurt. So, is my simple definition correct?

Positive offset = Shallow face
Zero offset = simple, dead nuts centered
Negative offset = Deep face

Thanks

 

Then this is wrong @Moriarity ? Why my head hurts continued.

 

The problem is Back Space these day’s are to the outer edge of the wheels lip. Years ago it was at tires bead.

 

Yes, clearly stated in description.

 

I think I got this off the TireRack website. Looks like you're right Johnny Gee!

 

Oh sorry @Moriarity, but that answer was incorrect.
We were looking for "Reverse is a negative offset, negative offset".
Congratulations to our reining champion @Johnny Gee.

Thanks for playing and join us next time for another exciting round of
HAMB trivia.

 

If it’s for a trifive, use this tool:

https://www.trifivechevys.com/calculators/rearTireCalc.htm

 

No contest here.

This is Cragars over wording in my opinion vs the few words to say the same thing I opened this thread with.

 

Screw the offset bullshit!!! My brain works in terms of wheel width and backspacing. I don't care where they measure from, as long as I know where they measured from. Why would I care what the offset is? Most of that crap is stupid metric. Rear wheels need a little deeper dish since they should be wider. Because in most cases that just looks cooler.

 

That is also backwards from what I understand. I guess backspace is the only way to describe it now.

 

I always use backspace, which has been from the edge of the backside of the wheel, to the mounting surface, for a long time...

 

I agree. But as I mentioned earlier. I wanna know where the tire sets. I can’t do that with an outside of the lip back space measurement.

 

But now according to what Johnny posted it is measured to the outside lip....

 

Which is stupid depending on the width of the lip

 

I like frontside/backside, sounds kinda dirty don't it!

 

I edited my post.

You can do all the math off the back spacing number. You'll probably end up calculating an offset, but since you are the one who figured out what it is, you can use your own definition of which direction it is. Just ignore the published offset number, since you don't really know what it means.

(btw the modern definition of offset has to do with how far out the mounting surface sticks out from the center of the wheel--so a positive offset has less dish than a negative offset wheel)

 

Exactly. Summit, Jegs, Cragar ect ect all use the outer edge of the lip. Years ago it was from the inside of the lip.

 

I don't recall ever having interference between a wheel lip and the wheel opening.
The sidewall of the tire on the other hand................!

 

I get it Denny . but the measurement could change from say 3/8 to 3/4 depending on a steel wheel or an aluminum wheel...

 

The offset is totally a newer confusing dimension. Backspace is always what we used to go by. Now all the new cars flush the rim out with no deep dish look any more. It's a stupid look.

 

its because of the axel and bearing.... neg off set means more stress on the axel and bearing... positive means the wheel center is under the bearing and axel flange... pretty simple when you think why...

 

Like Jim is saying, I’ll come up with my own figures.

Since Cragar uses metric numbers in their catalog which further complicates things I’m going this route.

I’ll order my front wheels only first (still free shipping) then I’ll know exactly how wide the lip is and go from there with my math using just backspacing. Then order rears (still free shipping). Win, Win and Win.

 

I just use the online metric conversion...

 

Summit uses SAE and Cragar Metric. If you use online conversion, guess what? Someone is rounding off. So which measurement is correct???

 

One thing to consider is when comparing wheels is the offset measured at the wheel bead, or the face of the tire bead. I once bought a new set of wheels replacing the wheels I already had. The new wheels were listed the same offset as the first set but they were 1/2” different and I had no room to spare with the old wheels. I started making calls and found out that the first set was measured from the bead, and the second side was measured from the outer edge of the wheel. Of course the tires were mounted prior to find this out so I own them.

 

ahhhh the ones that fit your car???? if you think you that .05mm will affect the set, you might just wanna go to a tire store and measure for yourself... or let them do it..