CRF 250L 120/90/18 Tire



Have a 42” rear sprocket and 120/80/18 rear tire. If I install a 120/90/18 does that change gear ratio?

Since sprocket is attached to wheel not sure that it does ?

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Gary 3 years 6 Answers 597 views 0

Answers ( 6 )

  1. Yes, but probably not enough that I would worry about it.

  2. It should as the overall tire diameter has theoretically changed by 10% x 120 x 2 = 24 mm (1″). You will travel ~ 3″ further on a single rotation of the wheel. This all assumed the tire brand and model is identical.

  3. Yes, the tire is now taller…90% of 120 instead of 80% of 120. It will change effective ratio and will feel like you went from a 42 to 41 tooth rear sprocket…less than 3%…likely hard to detect.

  4. Thanks-may go back with 80:18 ??

  5. it does affect the gearing ratio but it’s not a huge change..install a 13 front tooth to go with your 42 rear sprocket and go with the 90 tire..that’s what I run and it’s great

  6. Yes but ever so slightly. You will not feel it. I don’t.

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