Tire Size Numbers

6 replies to this topic
  • skinner

Posted October 25, 2004 - 05:44 PM


How do tire size numbers work? For example, my bike comes stock with a 110/100 x 18. Now, I know that 18 is the wheel diameter. But what about the 110/100 ratio? How would a 120/100 be different from the stock 110/100? :cry:

  • BWB63

Posted October 25, 2004 - 06:02 PM


The first number is the width in mm 110mm wide the second is the hight as apercent of the width 110mm. Our XR650R can fit up to a 140mm knobby 140/80 18 that would be 112mm high.
The Tera flex is the biggest knobby tire that I know of that will fit 140/80 18 but it messures 146mm X 114mm high from the top of the rimand 126mm from inside the top of the rim. I have a new Maxis 7301 120/100 18 It is 133mm wide, 98mm from the top of the rim and 114mm from inside the rim. So, you can see the numbers are not allways what they are suppose to be.

  • skinner

Posted October 25, 2004 - 06:57 PM


Thanks. Does anyone know how "true" sizes are on Pirelli tires? Also, what about a 4.50x18?? I've been told that's about a 120/100 18. Sound right?

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  • BWB63

Posted October 25, 2004 - 08:20 PM


A 110/100 is a 4.00 and a 120/100 is a 5.00 sence or something like that here I have a chart
Click Here ->Tire Chart

  • NukBoy

Posted October 27, 2004 - 05:40 PM


What kind of tire are you looking for. I searched far and wide for anything close to a road race tire for the stock rims and its a NOGO. I can help you on road tire but nobbies I can not.

  • TimBrp

Posted October 28, 2004 - 03:40 AM


So what that chart says is that my new tire a 120/100/18 is the equivelant to a 140/80/18? Damn I'm in for some exhaust rubbing. I just order the MaxxCross IT, anyone have this tire? Will I like it?

  • BWB63

Posted October 28, 2004 - 06:54 AM


There are some here that love that tire.....It was made for the lower torque of the two smoke 250's...it works great on the XR400! If you ride your BRP like a XR400 you will be happy :cry: But, if your full throttle type of guy you will not like it. The power of the BRP bends the knobbies over. Way to much wheel spin if you get on anything semi hard. If it's always loose, no rocks, just good ol dirt, you'll love it...I hate it out here in southern California...today after the rain it would be fun...I was talking to Barnum two days ago and he hates it. He was telling me Maxis is having him test a new desert tire on his race bike :cry: well see how that turns out. I love there 7301HT for hard fire roads :cry: That thing is awesome. I also love the IRC M5B 140/80 for the soft stuff...can't be beet there but, for everything the Tera Flex rules. It has it's problems but, for the guy that wants to jump on his bike and go that's the tire :cry:
The chart is just for comparision to the old way! the first number now is the width in millimeters and the second number is a % of that for the highth. 120/100 is to be 120mm wide by 120mm tall (it won't be but close. 110/100 110mm wide 110mm tall, 140/80 140mm wide 114mm tall I think you get the picture. :cry:

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