GTR Wheel Offsets

[msv]

I did a search on this topic, and came up with a lot of results, but there still didn't seem to be a definitive answer on this issue.

I plan to fit custom wheels, but want to make sure I get the offset right. From the information on the build CD, and a measurement that Ted gave me for the distance from the rim lip to the tire bead seat, I arrived at the following:

Front (18x9.0")
Offset = 7 mm
Backspace = 134mm

Rear (18x13.0")
Offset = 48mm
Backspace = 226mm

These dimensions can be seen on the following drawing:


Does anyone have measurements of the factory wheels that can confirm this?

Thanks. Mark


>>> Edited by msv on Tuesday 24th June 17:19

[bluesatin]

Is it just me being silly or would it not be easier to ring the factory and get the answer

[ultimaandy]

I think it's in the manual!

[james]

From what MSV said, it would appear that he has read the manual, and called the factory, but he's got different answers.

In his situation, I'd be asking somebody to remove a wheel and get the tape measure out too

I have a Mk4, so it wouldn't be much point in me measuring my wheels.

[msv]

Thanks, James, I think we are on the same page

The 120mm and 130mm dimensions on the drawing above are what are shown in the manual.

What it states is "The recommended distance from the mounting face of the rim onto the hub to the outside of the outer rim is 120 mm front 130 mm rear." This does not get you to an offset measurement, nor backspace, which are the 2 measurements usually given to a wheel manufacturer when getting custom fitments. From the measurement that Ted gave me, I calculated what the offset and backspace should/would/could be.

Before I send specs to a wheel manufacturer and have a very expensive set of wheels made, I would like to verify an actual measurement off of an actual wheel.



>> Edited by msv on Friday 20th June 23:39

[msv]

One of the members here was gracious enough to measure his wheels for me.

The measurements he provided were different than the information provided in the build CD, especially for the front. It even seems that the front wheel is not a 9" width as I had thought.

The measurements that were provided were the front space and backspace shown below, and the offsets have been calculated from these and the distance from the rim lip to the tire bead seat. Here are the results:

[Steve_D]

Sorry to add further confusion but my dimensions are different again. These rims date back to 1999.
Both wheels have the same hub to outer rim 128mm.
Front hub to inner rim 120mm.
Rear hub to inner rim 211mm.
Steve

[msv]

Steve_D said:

Sorry to add further confusion but my dimensions are different again. These rims date back to 1999. Both wheels have the same hub to outer rim 128mm. Front hub to inner rim 120mm. Rear hub to inner rim 211mm. Steve

Please excuse me, but I'll be gone for a while banging my head against the nearest wall...

Thanks for the measurements Steve_D. It would appear that your front wheels are wider, and the rears narrower than those Michael measured for me. Your offsets would be approximately -4mm front and 42mm rear, assuming that the inner and outer rim sections are comparable outboard of the tire bead seat. At least the location of the outer lip of the wheel is consistant.

Would anybody else like to join the fun and either add to the confusion or help to clear it up Thanks again to everyone.

>> Edited by msv on Tuesday 24th June 20:48