Factory Reproduction Wheels offset/backspacing

[Aurora40]

Originally Posted by Jeffvette

Based on my rough calcs, it's a GS offset wheel.

7.37 (backspace) minus 5.45 (10.9 Inside lip of wheel/2) = 1.92 * 25.4 = 48.76

Those wheels will be sunk in.

Yeah, that's what I was thinking. Offset is the distance from center. Backspacing is the distance from the edge.

Presumably the wheel is 11" wide, so the center is 5.5" from the edge. 7.37 - 5.5 = 1.87". 1.87" * 25.4 mm/in = 47.5mm offset.

But hell, I don't know. The real test might be just toss it on the car and see if it looks right.

[WVZR-1]

Originally Posted by Aurora40

Yeah, that's what I was thinking. Offset is the distance from center. Backspacing is the distance from the edge.

Presumably the wheel is 11" wide, so the center is 5.5" from the edge. 7.37 - 5.5 = 1.87". 1.87" * 25.4 mm/in = 47.5mm offset.

But hell, I don't know. The real test might be just toss it on the car and see if it looks right.

Bob,

I'm quite "confident" of my math and the calculating "scheme"! You need to use the "total" width of the wheel which is 12" to calculate "backspacing"!

I was rather dumbfounded when I stumbled on the calculator later this morning. You need to use the calculator yourself because it has some interesting results. It will +1 and +2 wheel diameters and give "mathematical" tire equivalents for you if you like. "Mathematical" possibilities some/most of the results aren't available in the "real world"!!

It's worth a trip to the calculator!!

http://www.bigcustomwheels.com/info_specs.jsp

-Dave

[Aurora40]

Originally Posted by WVZR-1

Bob,

I'm quite "confident" of my math and the calculating "scheme"! You need to use the "total" width of the wheel which is 12" to calculate "backspacing"!

I was rather dumbfounded when I stumbled on the calculator later this morning. You need to use the calculator yourself because it has some interesting results. It will +1 and +2 wheel diameters and give "mathematical" tire equivalents for you if you like. "Mathematical" possibilities some/most of the results aren't available in the "real world"!!

It's worth a trip to the calculator!!

http://www.bigcustomwheels.com/info_specs.jsp

-Dave

Yeah, that's a pretty cool site. So what does the 11" width refer to, the width between the start of the flanges/seats?

[WVZR-1]

Originally Posted by Aurora40

Yeah, that's a pretty cool site. So what does the 11" width refer to, the width between the start of the flanges/seats?

That's pretty much it and you'll see it displayed on the top of the wheel/tire image of the calculator. These calculators are quite interesting, it used to be "paper/pencil/the mind!

Most people that have problems with "wheel fitment" actually try to work with "offsets" and if you deal with primarily "backspacing" the confirmation of dimensions is much easier. Fitment is the "entire wheel/tire" combination not just the mounting flange width which is used primarily to supply the "section width" the tire manufacture desires for the tire size.

[npritchard777]

Found my tape measure! The backspacing is approx 7 7/16 or 7.4375. They should fit.



Thanks all!

-Nate

[Jagdpanzer]

Originally Posted by npritchard777

Found my tape measure! The backspacing is approx 7 7/16 or 7.4375. They should fit.



Thanks all!

-Nate

Close enough for government work!

[WVZR-1]

Originally Posted by WVZR-1

If they measure something close to 7 7/16" for a "backspacing" you will be fine. There's certainly a good bit of confusion "still"! The "ONLY" confirmation is do the "measurement" your self! To hell with labels and ads- get out the "measuring device" BEFORE- you mount tires! It's really that easy!!!!

I believe this to be the correct math: 36 /25.4 = 1.4173+ 6.0(12.0/2.0) = 7.417 +/-

It's good your "tape measure" confirmed!