Tire Questions....

Ok guys, I've successfully dual sported my '04 WR450. It is still riding on the stock tires which are not made for pavement at all. I've been looking at some tires and don't know which tire, nor what size is best for me.

The Michelin Sirac looks pretty good as does the Avon Gripster AM24. To me they look better for street riding than the Dunlop Trailmax.

Also I've noticed that these tires don't come in the exact sizes as what my bike came with. They are all lower profile which stands to reason for a more street oriented tire. My stock rear tire is a 110/100/18, I don't want to run anything thats' circumference is less than that.The bike is already turning several RPMs cruising at 60 mph. What size would I need in an 80 series profile to equal that circumference, a 130??? Will a 130/80 fit on my WR? I'm not real concerned about the front sizes as they don't effect gearing. It appears that a 90/90, or 80/90 is about all you can get anyway.

What's my best route as far as tires and sizes?

U.K. Stock tire is 130/90-18 as fitted to mine an i runs fine.

That's good to know. I will probably run a 130/80.

The funny thing about siracs is that they feel excellent on pavement. Then, when you jump offroad. You are first very careful because you have the picture of the tire in your head: no knobs. Then you realize the bike is really stable. So stable that the first time I almost stop just to make sure I was running the siracs... These tires are excellent on the road and very surprising off road. I would guess that the dunlops 604 (no mistakes:604) are really good too because they seem to be built the same way.

The size I have been using is 120.

Can any of you resident gurus tell me how much, if any, will my gearing be lowered if I go to a 120/80 rear tire. The stock rear on my bike is a 100/110.

I think I'm gonna try some Duro Median HF904s and the 120/80 is all they make for an 18" wheel.

The 120/80 tire is 96mm high from the wheel. The 110/100 is 110mm high from the wheel. Taking the 18" diameter of thh wheel plush the height of the tires gives you a total diameter of 18" + (96mm x 2) and 18" + (110mm x 2). If my conversions are right you are looking at a total wheel and tire diameter for the 120/80-18 of about 25.5" whereas the 110/100-18 is about 26.6". So going with the 120/80 will LOWER your final drive ratio by 25.5/26.6 or a factor of approximately 0.96.

Wow.... what did I just tell you... I am pretty sure nothing!! I guess what I was saying is that for every turn of the rear wheel the bike will only travel 96% of the distance with the 120/80-18 as it would have with the stocker 110/100-18.

So if your math is correct I need to run a 4% higher gearing set-up if I go with the 120/80. (in order to match the gearing with stock tires)

The more I ride the WR on the street, the more I think it needs to be geared a little taller. So, if I run the 120/80 rear, and go up one tooth in the front. How much taller will my overall gearing be???

BTW, the bike is a blast on the asphalt. Even on knobbys!!! :thumbsup:

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