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18" rear rim

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So im working very hard to make my 02' 250 trail worthy. I have put a lot into it. Just wondering......... how big are the bennifits of changing over to an 18" rim? Im sure more low end, but how sugnifigant? Thanx!

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More sidewall for better flex better for off road less chane of piching the tire against the rim on rock Logs ECT that less chance of flats Stronger shorter spokes, more choces of tires and tires are cheper to buy.

The wheels I have came with a 19 inch when I need a new rear wheel I will change it out to a 18 get rid of the stock 19.

Botton Line 19 inch better for MX/SX type racing and 18 inch better for offraod type riding.

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I wouldn't worry about it unless you are going to do some very competetive riding. I've heard of pros running 18 inch tires on 19 inch wheels. not sure exactly why but that makes me think a 19 inch rear wheel is fine for just about anybody.

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The 18" rear wheel was a great improvement over the 19" that was originally on my 01 cr. It is smoother it brakes better and the traction is better. Maybe for supercross or some motocross in some situations the 19 may be better. ..For offroad the 18" is great. I got the wider 18" too. I think it is the 2.50 :worthy:

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I wouldn't worry about it unless you are going to do some very competetive riding. I've heard of pros running 18 inch tires on 19 inch wheels. not sure exactly why but that makes me think a 19 inch rear wheel is fine for just about anybody.

18" tires on 19" wheels? Explain further please. How is that supposed to work ?

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18" tires on 19" wheels? Explain further please. How is that supposed to work ?

You could never get a 18" tire on a 19" rim.......

As to how much better a 18 is over a 19 off road, I think theres alot of other things that will make a bigger diffrence that just changing the rear rim.

You will not get more low end power with a 18" rear tire...... the overall height is the same between a 18 and 19.

I would change to a 18 when the rim is wasted and needs to be replaced

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Ok. I've just read where a lot of guys have taken an mx bike, and made them woods worthy have changed to an 18''. There must be a good reason, cause thats what the off road bikes usually come with. Thats what my KDX250 has on it, along with the KTM's. Just seems to me if you have a smaller rim, the wheel is going to turn quicker, equaling better bottom? IDK, i'll keep searching.......

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Just seems to me if you have a smaller rim, the wheel is going to turn quicker, equaling better bottom? IDK, i'll keep searching.......

Your right the rims are smaller, but the sidewall heights on 18 inch tires are taller. In the end the total heights are pretty close to the same.

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ohhh! I gotcha! So the biggest bennifit would be the with the taller sidewall, the less of a chance for a pinch flat? Would an 18 hook up better?

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Some are believers and some are not. The only way is to ride one with an 18"rear wheel with a good tire through some good single track.

If I rode MX or SX, I would of left my bikes alone with 19"rim. But I'm a trail rider and like to climb hills. For me the 18 is the way to go.

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Would an 18 hook up better?

I was reading in another thread that the taller sidewall allows you to run a lower pressure. So that in turn will give your tire a larger foot print, so yes more traction is a possibility. Pretty sure it is similiar to the trials tire theory.

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I wouldn't worry about changing the rim until you break your 19. If you ride your bike hard on trails you will break rims so just change to the 18 at that time.

As for running lower pressure offroad, you can't really do that. You will get pinch flats. Run 12-14 psi on smooth stuff and if there are any rocks, roots, or ruts involved you're going to be running 16+ psi. It's a survivability issue, not a traction issue.

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I re-laced an 18" wheel on my bike, but only because 18" tires are cheaper and I already had about a dozen new 18" tires in my garage. The 19 works fine offroad. I run 12lbs all the time with either 18" or 19". I use a Moose HD tube and haven't had a pinch flat in 2 years (knock on wood), same tube- gone through 8 tires (the tube was a 19", and I'm using it in my 18" tires now.

The difference in feel between the 18" vs. 19" is pretty subtle. It's most noticeable through the rocks- it absorbs better and stays straighter and just feels "cushier". The downside is the 18" tire weighs more and that rotating mass tends to do funny things in the high-speed whoops, especially under hard acceleration. Can't say for sure I can attribute that to the tire, but I didn't notice the rear-end swapping with the 19" like I do with the 18". The 19" feels better than the 18" in deep sandy whoops and on loamy dirt.

From my experience, overall, I'd say the biggest benefit of the 18" over the 19" is the cost. The 18" tires seem to be about $10 cheaper than the 19's. But it will cost you at least $100 to do the swap- that's if you lace the rim yourself.

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I have a KTM 300. I recently borrowed a buddy's 19" rear rim and tire. We went to a friends farm were we have an enduro loop complete with logs, rocks, hills, and single track. the parts I had difficulty with when I had my 18" rim mounted I found to be easier with the 19" rim. I measured the diameter of the tire, and the 19" is 1.25" larger than the 18". Is there any technical info to explain this, or was i just having a good day?

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I have a KTM 300. I recently borrowed a buddy's 19" rear rim and tire. We went to a friends farm were we have an enduro loop complete with logs, rocks, hills, and single track. the parts I had difficulty with when I had my 18" rim mounted I found to be easier with the 19" rim. I measured the diameter of the tire, and the 19" is 1.25" larger than the 18". Is there any technical info to explain this, or was i just having a good day?

There's a couple of factors that could come to play. Maybe you did have a good day. Maybe it is the tire. Maybe the tire pressure. I run around 6 lbs on my 18 on my cr 250 but that is for the slippery wet clay stuff that we have here. You may have totally different soil so it may be a big difference for you. The 18 makes a big difference for me. It is smoother. It brakes better and hooks up better over roots,logs and rocks. I like the Pirelli mt16 as probably the best all around tire. I also got the wider rear rim so there is an even wider track. You could check my TT garage to see how it looks but I think I had an IRC MB5 on there at the time of the picture.

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You could never get a 18" tire on a 19" rim.......

As to how much better a 18 is over a 19 off road, I think theres alot of other things that will make a bigger diffrence that just changing the rear rim.

You will not get more low end power with a 18" rear tire...... the overall height is the same between a 18 and 19.

I would change to a 18 when the rim is wasted and needs to be replaced

haven't you learned, never say never, just when you think-some idot will prove you wrong. friend of mine bought a bike, when I looked it over:jawdrop: we cut the 18 off with a disk wheel. 18 on 19, probly with a machine it could be done

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I dont know if any of you have tried a trials tire on a 18. And to my knowledge I dont know if any tire makers make a 19" trials tire. But after I tried one I was hooked. What a difference in the tree rooted trails and rocky trails. Even for hill climbing it worked great. Down fall of the tire is its hard to put on, dont do any high speed stuff. Just my two cents.

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I dont know if any of you have tried a trials tire on a 18. And to my knowledge I dont know if any tire makers make a 19" trials tire. But after I tried one I was hooked. What a difference in the tree rooted trails and rocky trails. Even for hill climbing it worked great. Down fall of the tire is its hard to put on, dont do any high speed stuff. Just my two cents.

I was about to say, one of the reasons I've been looking into changing my rim to an 18" is to put trials on my bike. I ride in Alberta, mainly the single track at McLean Creek and the terrain is optimal for a trials tire from what I've read (when it's not muddy).

The main reasons I've heard; taller sidewall allowing to run lower pressures, cheaper tire prices (how often you changing? will it offset the price of the rim/hub etc.), and trials.

Let us know if you do change and what difference you notice.

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ohhh! I gotcha! So the biggest bennifit would be the with the taller sidewall, the less of a chance for a pinch flat? Would an 18 hook up better?

Additionally the 18" rear provides a little extra compression with in the tire in rough terrain. Think of it as a 1/2 " more cushion for the pushing. Additionally more sidewall flex for better traction.

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