2005 crf450x tire size recommendation

i have a 2005 crf450x with stock rims and tires, i am looking to get a second set and was wondering if i should stick with the stock size or if i should change to a different size? does it affect the performance or handling? and if it does how much will it affect it?

Stock size is fine for most applications.


110/100-18 and 80/100-21

Modded engines and racing applications might call for bigger tires.


120/100-18 and 90/100-21

I use a 120/100-18. Love it!

The weight of the tire and tube definitely affects performance.  I ran a Maxxis SI 120/100-18 with an ultra heavy tube and hated it.  It felt like I installed a second flywheel.  Straight line traction was good but that's about it.  I learned first hand why so many people are concerned about un-sprung weight.  I recommend you find a stock size tire that you like that fits your terrain type.

There's a little more to the choice of tire sizes for the 450X.

True, putting a "desert" style 120/90-18 rear tire and an ultra heavy duty tube on your bike will behave differently, but not necessarily "better" or "worse". True, You can add pounds relative to the stock 110/100 -18 MX style lightweight tire and thin OEM tube.

The added rotational inertia will resist quick leaning over more than a lighter wheel due to the gyro effect. It will also accelerate slower due to the added rotational inertia. And, since its unsprung weight, it will also affect your rear shock settings.

However, it has a larger contact patch with the trail, providing better traction in loose stuff.

The added rotational inertia of a 120/90-18 isn't an issue for me. I can break the rear wheel loose at any time by quickly rotating the throttle. My WR250F handles a 110/90-18 or 110/100 -18 tire just fine.

The added gyro effect is the big negative, but I accept that for the improved traction. An HD tube like a Kenda Tuff Tube has been my choice. I haven't found a need to run an ultra HD tube.

So, like most changes to your bike, its highly dependent on your riding style and preferences. If its important to you to improve traction, run a 120. If you're happy with the traction you are getting but want to turn quicker, try a 110. Ride and decide!

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