Just put 1 on mine. I bought a 2010 and it still had the factory tires on it. Date stamp said they were made in 2009. So far I'm diggin it. Of courseanything would be better compared to the piece of shit that was on there. Went with the Bridgestone Battlax Adventure A41 for the front.
The Bridgestone site does not show it as being a radial. 90/90-21 M/C 54H W is not a radial as far as I can find. The letter “R” shows the tire construction type as ‘radial. The 90/90/21 is the only A41 tire not designated as "R" radial. I hope I'm wrong because I would like to try a radial front.