I have always run the +10mm on the rear of my 550's. Seems to wrk well. My sis 500 we put the 140 on iirc. Not much room on the swingarm for anything bigger and the rim needs to be wider to fit anything wider than +10 over.
A 140/17 combo will work but a 150/70 is to large. However a 150/60 will work. Thats what the racers use, i have one as well, fits like a glove. Its very popular amongst all the 500 riders i ride with....and the ex500riders.com website. I am running 150/60/17 Michlein pilot roads...which are no longer availble but were replaced with michelin pilot powers.
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