I have been thinking about using an 18 inch rear rim to lace onto my front wheel. I would then have a very cheap "supermoto" Am I trippin'? I have heard of people using 18 in the back and 17 in front, what about 18 in front and back? are there issues with doing this? I can't figure out why not- would I need to install a stabilizer in front?

thanks

I saw some short track racing they were using 18" front and rear so it is possible .
I think CCM made a bike with 18" wheels.

Your biggest problem with an 18" front will be your choice of tyres, and the profile of them. 18" tyres tend to be designed as a rear tyre, and so have a rounder profile than a front tyre. The more triangular front profile is to help the front to drop in to a corner, a rounder profiled 'rear' tyre may be a bit of a struggle to change direction with.

I'd give yourself as much tyre choice as possible with your rim sizes, that's why supermoto's tend to go for 17".

If you already have an 18" rim with the correct number of holes, then I say just go for it. 18" front and rear will work fine. There are plenty of excellent bias ply tires these days, you don't need expensive 17" wheels, with silly-sticky tires, to have a kick-ass backroads toy. I'd recommend sliding the forks down in the triples to be flush with the top of the triples and swap in a stiffer set of fork springs. If you can find a spare shock, have a suspension guru revalve it and/or swap in a stiffer spring. Add a set of Race-Tech cartridge emulators in the forks and you have a very capable sportbike. We roadraced similarly set-up dirt bikes for years...
Here is a photo of my '92 XT600E faux Motard; shown with a stock-sized, skinney 17" rear and skinney 18" front rim. The tires are Bridgestone BT-45 on the rear (120/80-17) and an ancient Metzeler Lazer (90/90-18) in the front - not the stickiest bias ply tires but it still will rail thru the corners. Totally stock suspension. It kicks ass...

I've since gone to a 19" front which came to me with another XT. I prefer the 19" slightly on this bike since I feel like there is more feedback than with the 18". Keep in mind my '92 has slightly different geometry than your '89 and also a 17" rear.
I've never needed a steering stabilizer on this bike, but YMMV. Carefull tire selection makes a big difference, since some tires are more prone to instability than others. You actually will probably prefer a rounder, slower steering front tire, since it will turn so much quicker than with the stock 21". Good luck!

i have seen a couple of xt's using rims off a street bike, i think gs500 wheels, im trying to find out what wheels they are using, so i could swap. i would love to keep it off-road, then change to motard for street

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1990 xt600

My 89 tenere is fitted with 18" akront rims laced to OE hubs.
seems to suit the bike for road biased riding
I'm finding that pirelli scorpions work very well.

Just throwing my 2 penneth in after struggling for ages to find street wheels to smooth out the bump of knobblies. I fitted Suzuki RG125 Fun wheels to mine. They take exactly the same wheel bearings which lets you know you can use the same spindles. They will also take a 110 front and even up to a 150 on the back. Aligning them was a bit of a stuggle as was sorting the rear disk brake and the front caliper (my bike was a 1987 tenere orignally) and there was a lot of messing about making up spacers but now it handles as smooth as silk and you get a good choice of rubber. I love it now - when it has a spark - which is why I was on the forum in the first place - Hey ho!

I've tried to attach a pic so you can see what it looks like. Good luck with your conversion!

I'm struggling with the pics so send your email address if you'd like to have a look.

!

Seems the pic worked after all!