Originally Posted by BMW-K
No. More like I'm not sure the 21 is necessaray. I've seen several GS's do the TAT on 19/17's.
If it's an absolute necessity, then that changes things. Kinda like the Haul Road - there's no need for a 21 at all. Fact is, if it's dry out you can run the Haul Road on Slicks.
I can confirm that, as I did Haul road on the stock GS rims and Bridgestone 501/502's. Most of the TAT is doable with the big bike too, as long as you keep an eye on the weather. You know the 'pig' likes rolling in deep mud a bit.....