My friend has a Yamaha Big Bear and he cut a tire on the last ride. he went out today and bought a new set of tires for the rear. He bought GBC Dirt Devils in the 25X10X12. We got to looking and the GBC tire has a more flat carcass than the stock Dunlops. There is about an 1" difference between the two tires. My question is will this effect the four wheel drive ratio? He still has the factory dunlops on the front. Does he need to replace the fronts also? Or will he be okay with the two tire sizes?

 

It shouldn't affect it a whole lot. I was told that the best way to tell was to find a nice, long, straight stretch of trail. Try running it at different speeds, and see if there is any handling problems. Basically, if the rear end tries to pass the front, he might have to play with different tire pressures until he gets it pretty close. It sounds logical anyway. Might be worth a try.

 

Anytime you change the tire size like that, the smaller tires are going to be turning faster than the taller tires. This will be hard on your drivetrain and will make your tires wear faster. Playing with the air pressure to get them all the same height would be a temporary solution, but I would put the same height tires all the way around. Naturally, the greater the height difference the more severe the wear and strain...especially on pavement.