Help identify these wheels please. Offset etc

[mike_nofx]

Hi, was wondering if anyone can help me identify the offset of the rims fitted to my Sierra, and also help me understand how offsets and rim widths are measured.

Inside the rim is stamped:
7JJx15 94 11 29 v F Made In Taiwan ROC

I took some measurements to try identify the offset. I placed a straight edge across the lip of the rim, and measured down to the face which bolts onto the hub.
I measured from the inner and outer lips to the same point (the point being the face which bolts to the hub).

The inner lip, to face measured 88mm
The outer lip to face measured 120mm.

So by my measurements (which were close, but not 100% accurate), the rim width, lip to lip is actually 208mm (or just over 8") but im guessing rim width isnt measured lip to lip.

Also, i have 33x12.5" tyres fitted to these rims, is 12.5" tyres too wide for a 7" rim?

What does JJ (as in 7JJx15) and all the other numbers stamped on my rims mean?

Thanks
Mike

[CWBYUP]

they are 15 x 7 but cant help with offset.

Nick

[chrispie123]

jj stands for double safety lip

[Slunnie]

Rims are typically 1" larger than their marked size for the reasons you've said - its a bead to bead measurement.

Offset is the distance the hub mating surface is away from the centre of the rim. In this case your rim is 208mm wide, centre line is at 104mm, and your hub mating surface is 16mm away from the centre line. Because your hub mating surface moves the rim away from the vehicle from the centreline, it is a negative value offset

ie, your offset according to your measurements is -16mm