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Rear tire sizing-140/80 same as 120/100?

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I'm a little confused about tiring sizing, and have read that a 140/80/18 is the same as a 120/100/18 overall size, rotation speed etc. I'm looking to replace the stock metlzer 140 on my 525exc and want to make sure a 120/100 will work ok. Is the 140 still wider:excuseme:

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I running a 120/100-19 on the rear of my bike Seems to work fine.

But what I have been finding out with this much power these big bore KTM put out I be buying lots of rear tires it's fun riding but rear tire get expenisive I am trying a Dunlop Desert tire now I don't think It going to last much longer than the cheeper tires do.

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It almost always depends on the rim width. If you put a too big tire on a narrow rim( like the 2.15-2.25" KTM rims) then it will squeeze the tire and you will end up with a narrower but TALLER tire.

For example, I am running an Interco Tera-Flex 150 on my rim. It is squeezing it so much that it probably measures more like a 130/100/18, because it is supposed to go onto a 3-3.5" rim.

The first number is the width in millimeters( 140 mm) the second number is a percentage of the first number for the height of the tire from the rim to the outer most circumference of the knobby (sidewall height)

So in the case of the 2 tires you are talking about the 140/80 is still wider than 120/100 because the first number is 140mm wide. Now the second number will give you a measurement that will affect your overall speed and affect whether you have lower gearing for wood, or higher gearing for highway.

The 140 you had gave you a sidewall height of 112mm, and the second tire(the 120) is 120mm in sidewall height.( this will give you more highway gearing)

Now remember the first thing I said about rim width and the SQUEEZING effect, well if you go any wider than 140 on the stock KTM rims, you will end up affecting the final ratio for your gearing.

Hope this helps a little?

Have fun !!

👍

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There are 2 methods used to size tyres. That is why

130 = 110

140 = 120

It depends on which method the manufacturer uses.

With Michelin they will have a size eg 130/80x18 and then have a small sticker with the other measurement eg 110/100x18.

I am not positive on the measurement process for each but I believe that one measures across the actual tyre not including the knobs. The other is the measurement including knobs.

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Yes you are right. A 140/80 is approx same size as a 120/100. YES, you can use a 120/100X18. I ran the Pirelli MT16 120/100X18 on my 525EXC and loved it.

Dwight

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