my 91 500 has smaller tires then the 97+ or whatever it is, so i went to 130 rear and a 120 front... Seems to work well, i dont use that for a twisty bike its a commuter so the bigger tire should last longer and its more stable to go striaght....Got my Z1000 for twisty and stuff and 500 cuz insurance is less for a year then my monthly truck insurance...plus it can go 220mi on a tnak with it modded....My Z1000 would be 80mi back with an empty tank...love the 500...keep it stock..i htink u cant go bigger unless the newer ones have bigger fenders.. cuz i know i went as big as i could on the 500 and thatso nly going to 97+ model rear and 10mm wider front