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natblazer

why an 18 inch wheel?

11 posts in this topic

From the new guy interested in a new wr450 i ask, whats with the 18 inch wheel? A salesman at yamaha has no better explanation than because there are more tire selections in that size, but im not buying it. Or maybe there are, but i still want a 19 inch rear wheel. Shouldn't I?? Will a 19 inch wheel fit on the wr without hassle?

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You don't get as many flats with an 18" rear wheel. There is more rubber on the tire to cushion the impacts. MX bikes run 19" because of less sidewall flex.

I never noticed any difference though.

Your salesman dosn't sound like the brightest bulb on the chandelere.

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I believe the arguement that 19 inch tires aren't as available as the choices for 18 inch tires should have died years ago. I am sure that actually was the case in the first couple of years the manufacturers decided to go with 19' rear wheels for their motocross bikes. Now after several years of making those "odd" sized wheels/tires, there seems to be a lot of availability from different manufacturers.

My local dealership has plenty of 19' tires on hand but 18' tires have to be special ordered. Of course, my dealership sells mainly motocross bikes. I suspect this is becoming more apparent nationwide. Motocrossers usually are more in need of the performance a new tire offers compared to your average off-roader.

You should tell your salesman that the real reason Yamaha chose to go with the 18' rear is that the thicker profile of the tire allows more "cushion" against flats in high speed operations. 19' tires do have a much lower profile which is partly what gives them their advantage on new MX bikes.

I have no experience with changing over to a 19 inch rear with my WR, but hopefully someone in here will post who has. I would like to know myself. I seriously doubt Yamaha would have made it impossible to do so but will wait for the person who has actually done this to explain the particulars.

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Natblazer,

The 19 inch will fit fine. The rear end on the WR is the same as a YZF. As the previous posts say, the WR has an 18 inch rear because the sidewalls are taller, giving better protection against pinch flats from rocks and roots.

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I'd say tires are made to fit the wheels. Not wheels for tires.

If a big side wall was needed for a 19 inch wheels, I guess tire cies could build it.

My understanding is that the 18 inch rim is less fragile to deformation than an 19 inch. The bigger the circle is, the easier it is to deform. The choice of the 18 for the WR probably comes from this arguement.

On the other hand, the bigger the wheel is, the better the torque on the groud is ( think about big farm tractor wheels ).

Guys doing competitons with YZs want the 19 inch to have maximum traction on the ground and care less about durability.

My WR has a 19 inch rear wheel. That allows me to buy used competiton knobby tires (almost new)for only few bucks and wear them on with no regrets even if I do some pavement. :)

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I put a 19" rear on my WR426. I bought an extra set of rims so I can run dual sport tires and change out quickly. The 18" has more selection for street type tires so I'm using the 19" for the dirt.

I was a little worried about he reduced sidewall height so I went with a 120 width Maxxis IT and the thing seems huge. I can't see how the 140 width even fit in the swingarm. It also rubs on my mud flap a little.

Overall, I haven't really noticed much of a difference with the 19" wheel. It may be slightly less forgiving but with this big tire and ultra heavy duty tube, I haven't had one problem and it gets great traction.

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I put a 19" rear on my WR426. I bought an extra set of rims so I can run dual sport tires and change out quickly. The 18" has more selection for street type tires so I'm using the 19" for the dirt.

Exactly what I did. Did not notice any diff either when comparing with the 18.

It is true that their is a lot more choice for street type dual sport tire in the 18'' size.

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Around here, even if a guys buys a bike with a 19" wheel they put a 18" on so they can get a 140/80 18" tire. :)

I always run the 140 and my mud flap is flawless. Luck? And yes, you do have to shimmy it into the swingarm.

BEEFY!!!

Isn't the 110/100 18", which is supposed to be the same as the 140/80 18", a bit smaller?

I put a new Bridgestone on last week and it seems a bit smaller. :D

Hoss

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Isn't the 110/100 18", which is supposed to be the same as the 140/80 18", a bit smaller?

I put a new Bridgestone on last week and it seems a bit smaller. :)

Hoss

The first number is width, while the second is aspect ratio or sidewall in percentage of the width. A 100/100-18 will be 100mm wide, sidewall will be 100% of the width, in this case, its also 100 mm high. Now if you do a 100/80, this means its 100mm wide, but the sidewall in shorter by 20% (80mm). I run a 130/80-18. Its wide, but low profile. The advantage would be stiff tire so you can ride in on a flat, no problem. Of course, sidewall is used to absorb impacts, so a shoter sidewall will be more likely to dent rims on rough trails. A 100/100 tire is about as tall as a 130/80, just not as wide. If one was to mount a 140, it should fit OK as long as you go with a shoter sidewall, ie 140/80-18 Of course, if its a 19" rim, it may not fit. :D

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