By my measurements, there are basically 3 front 4wd offsets. I currently own a B74.1, TLR 22-4 2.0, TLR 22X-4, Shumacher CAT L1 Evo and Xray '21 XB4C. I used to own an EB410 and D418. Yeah, I'm a little crazy...

Narrowest: Team Associated, Yokomo
Middle: TLR 22-4, HB Racing, Tekno
Widest: Schumacher, Xray, TLR 22X-4

Note that TLR changed the wheels on the 22X-4 about 1mm wider to match the Schumacher/Xray. Jconcepts says the 22-4 wheel (3327) is the same backspace as the Xray (Schumacher), but I don't agree.

This is also the offset from the center of the wheel, not backspace. Some of the wheels are slightly wider/narrower than others, which affects backspacing but not offset.