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Old 25 Apr 2021
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Question about tire size on front tire.

Hey guys, I have an X Challenge and it uses a 90/90/21 front tire.

I have a 80/100/21 tire that I want to mount and I just wanted to double check that it would still fit the rim okay?

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Old 20 Jun 2021
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I don't think it will be a problem, I will do this on my GF's Xchallenge next week. My own R65GS will also get an 80/100 tyre on a 21" front wheel.
R65GS + R80GS Basic
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Old 26 Jun 2021
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I have another question about the rear tire this time.

The X Challenge stock rear tire size is 140/80/18

I saw a TKC80 tire for sale for a good deal and it is a 120/90/18

This 120/90/18 size is pretty common for KTM's which might equal spending less dollars.

Would the narrower tire still seal well against the rim?

Please feel free to point out any issues.

http://www.journeyrider.net Latin America blog (07-8)
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Old 27 Jun 2021
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Hi Gato:

The size differences between the tires you propose using (both front and rear) are very small, and in each case you are proposing to use a narrower tire, so physical fit should not be a problem.

But... there are a couple of other things you will need to investigate:

1) Check the load rating of the tires you propose to use, and make sure it is equal or greater to the load rating of the OEM recommended tire.

2) Be aware that on motorcycles, a small change in tire width and/or profile can result in a large change in handling characteristics. This change might be exponentially bigger if you use non-spec sizes on both the front and back at the same time.

Concerning item 2) above, I suggest you visit a model-specific forum for your particular motorcycle and see if anyone else has prior experience using narrower tires - and find out what their experience has been.

Personally, I don't think it is a good idea to use non-OEM spec components on critical safety systems such as tires, brakes, or bearings. Chances are that the price difference is not significant (it's unlikely you are looking at $100's of dollars of savings) - if it was my bike, I would stick with the OEM spec unless I found pretty solid and trustworthy evidence that the different sizes you propose do not create unexpected handling problems. By that I mean reports from more than one rider that the sizes you propose to use work OK, last equally long, don't mess up handling, etc.
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Old 4 Jan 2022
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Originally Posted by gatogato View Post
Hey guys, I have an X Challenge and it uses a 90/90/21 front tire.

I have a 80/100/21 tire that I want to mount and I just wanted to double check that it would still fit the rim okay?

what is the advantage of using a 80/100 x 21 tire?
bernardo feio (Portugal)
2.5 Land Rover Lightweight / BMW R80 G/S PD / Toyota HZJ 78
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