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Hello,

Its me again, asking questions. LOL

The manual states my back tire should be 100/100-18, but when I just looked the tire is 120-90-19. Should I be concerned or replace?

Also, the back tire psi shows 19 psi and front tire is 10psi. The track I ride on is hard and dirt. I am still on beginner track. According to the manual, I should put both tires to 14 psi for my riding condition. I am not riding hard. I am mainly getting training now. I ride maybe once a week.

It's an aftermarket rim then, every kdx200 since forever uses Front:80/100-21 Back: 100/100-18

If it's not causing any problems like rubbing on the swing arm(120 is a wider tire) then keep it I guess..

Most recommend between 10-15 psi depending on the terrain. I have mine at 12

Gotanubike wrote:It's an aftermarket rim then, every kdx200 since forever uses Front:80/100-21 Back: 100/100-18

If it's not causing any problems like rubbing on the swing arm(120 is a wider tire) then keep it I guess..

Most recommend between 10-15 psi depending on the terrain. I have mine at 12

Thank you.

So my rim is not made for 100/100-18?

Should I buy a the correct size rim for the bike? No there is no problem with rubbing.

your rear wheel should be an 18, every kdx uses an 18 inch wheel unless someone threw a motocross wheel on there. as far as sizing goes, I'm running a 120/80 right now with no problems, and a 110/100 before that. I like the extra traction, also having a slightly modded bike helps spin up a larger tire. if you're stock, stick with a 110/100, 110/90 or 100/100, smaller tire and easier to spin up. I keep my tires around 10 psi for trail rides and around 14 for track days

goodoboy wrote:

Gotanubike wrote:It's an aftermarket rim then, every kdx200 since forever uses Front:80/100-21 Back: 100/100-18

If it's not causing any problems like rubbing on the swing arm(120 is a wider tire) then keep it I guess..

Most recommend between 10-15 psi depending on the terrain. I have mine at 12

Thank you.

So my rim is not made for 100/100-18?

Should I buy a the correct size rim for the bike? No there is no problem with rubbing.

You probably have the stock hub, someone just laced on a larger rim.

Tire size is measured:

100/100-18 =

100= width / 100= percentage of width that is the sidewall height -18 = rim size

To me, anything over 12 psi is too "skaty". I generally run 8.5 rear and 9.5 front with heavy tubes.

Likely just a KX rear wheel thrown on. The KDX and KX have the same rear axle diameter. (I am using a KDX wheel on my KX based hybrid with the KX axle/adjusters/spacers). A 19" is fine for the track, and will probably be fine for the trails you'll ride in that part of the country. Lots of folks prefer the smaller 18" rim because it allows you to run a higher sidewall tire resulting in fewer pinch flats. A 120/90 is a big tire, but if you're not having clearance issues with the swing arm I wouldn't worry about it. And no, your rim is not made for a 100/100-18.

bufftester wrote:Likely just a KX rear wheel thrown on. The KDX and KX have the same rear axle diameter. (I am using a KDX wheel on my KX based hybrid with the KX axle/adjusters/spacers). A 19" is fine for the track, and will probably be fine for the trails you'll ride in that part of the country. Lots of folks prefer the smaller 18" rim because it allows you to run a higher sidewall tire resulting in fewer pinch flats. A 120/90 is a big tire, but if you're not having clearance issues with the swing arm I wouldn't worry about it. And no, your rim is not made for a 100/100-18.

Thank you.

I just put the bike on the stand and turned the back wheel a feel times and I see no problem with rubbing against the swing arm. The trails I will be riding on will be hard Texas ground.

Like you said, as long as the tire is not rubbing aginst the side arm I should be fine.

With air pressure there are a lot of variables to consider. It is NOT one size fits all and your trainer should be helping you with this. Air pressure affects the way the bike rides as well as tire life.
Things to consider when selecting tire pressure;
Tubes (standard, heavy duty, ULTRA heavy duty) my general thought is the heavier the tube, the less air you'll need.
Tires, some have very soft side walls, some very stiff. Some tires are made to run super low pressure, some need a lot for the knobs to grab traction correctly.
Terrain, this varies so much from area to area, so taking my advice (NW trail rider) on tire pressure for your areas' (Hard pack Texass) dirt is not the best idea, but I can give you a range.
Suspension, this really matters when choosing air pressure. If you just had your forks tuned by a builder, you might ask him what PSI he recommends. The bike might "bounce" a bit at 14 PSI just because of the fork settings.

All in all, you should be checking your air before each "moto" or ride and adjusting accordingly. I ride trails, when I am going to a "new" or different trail system, I often leave the truck w/a little higher pressure, if I have problems with handling, I air down a pound or two at a time.

A good starting point is 14 PSI, you might want to start at 15 and then let a pound out at a time to feel the difference. Do the rear 1 pound, ride, then the front. Stop letting air out of any tire that is performing to your desire and work the other (most run a # or 2 less in the rear than the front....but not all).

It takes time to learn new things, so not all answer can be a "given", some must be discovered!

+1 to 6 Riders comments above. Experiment until you find what works best for you. Same goes for suspension, bar and controls setup, etc. Your "trainer" should be savvy enough to know all this, it is general off-road riding knowledge that applies no matter what type bike you ride. I keep an electronic notebook of all my rides...weather, trail conditions, time of day, riding group, etc.. as well as bike setup. The best advice is to get out and ride, change one thing at a time and ride some more until it's setup the way you like. then ride a lot more