Larger rear tire diameter question.

1 reply to this topic

Posted February 23, 2008 - 11:14 AM


Just a quick question regarding gear ratio. Have a 50 tooth rear sprocket coming and opted to keep the 15T c/s. The kind of riding I do requires mostly torque vs speed so increasing the rear by 5T should accomplish my goal. It's not uncommon for me to be in thick mud as deep as 8" for 30+ ft at a time bogging my way out throwin mud all over my son-in-law on his drz400sm. I'd also prefer having the most amount of rear tire that I can get to fit on the bike without having to make any major mods ie. a 140 or maybe a 150. Since a tire of that size would be larger than the oem tire (4.60) that is on the bike now it would surely increase the diameter of the overall tire. So the question is, would I be defeating the purpose of trying to gain more torque by increasing the rear tire diameter or am I thinking bass ackwards?

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • cleonard

Posted February 23, 2008 - 11:24 AM


You are backwards. A small diameter rear tire will make more effective torque. The tire to the ground is the final "gear ratio." In this you can think of the rear tire as the countershaft and the ground as the rear sprocket.

The percentage change withe the different sizes is usually pretty minimal. About like one tooth on the rear. The sizes on the side of the tire don't really relate very well to the actual diameter of the installed tire. The best place for this is the manufacturer websites. Most give this info there.

Related Content


Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.