[lil nick]

i know it doesn't sound good but i put a 180 on my 90 and it is so squeezed on the rim that it is flat across the tread, i wouldn't recommend it, i put it on because i wheelie and only run 10 to 20 psi in the rear so i have a wider footprint to ballance on.

[Sundowner]

I got 160's on both of my Post Kats maybe if i get creative i will take a couple pics when i go to the house and try and get the 600 to start today.

[hardlydangerous]

I have some 180 55 17 michelin pilot RACE and BT0-16 in my shop
Ill mount them and take some pics

trust me a 180 is way to wide for the rim and ballons the tire out.

as for wider foot print... a proper width tire for the rim and lower tire pressure will give you a bigger foot print then a huge tire pinched onto a little rim. the pinched tire has a smaller foot print and distorted profile.
the Conti motion and Road attack 170 are desinged for a 4.5" rim I prefer the 160 for handling