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2007 crf 450x tyre sizes

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hi folks,

my crf has a 140/80 rear tyre on now which needs replaced. Some please explain to me the difference in performance regarding rear tyres ?

ie 110/80 say vs my 140/80,

most of my riding will be on wet muddy plantations.

cheers

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Tire sizes are expressed as a width in millimeters (110) and then the size of the side wall as a percentage of that width (80). So 110/80 has a sidwall that is 88 millimeters. The larger the second number is, the "taller" the tire is.

You can only go so wide before it will rub on the chain, and only so tall before it will get too tight to the front of the swing arm.

Generally, you should stick with the tire size specified for the bike, unless you've modified it in some way (ie. different size rim). That recommendation from the MFG is based on a number of factors; weight, gearing, hp, torque, etc to give you the best possible performance.

Jim.

Edited by JimDettman
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thanks jim, will a narrow tyre help more with turning ?

In general, wider tires work better in sand and hard pack, narrow in mud. More important though is the compound (how hard or soft the rubber is), and to a slightly lesser extent, the pattern of the tread. Having the proper tire gives you traction to make turns.

But for turning, even more important then that is the basic setup of the bike (you've properly set your sag) and are using the proper technique for turns (weighting the front end).

Again, unless you have specific requirements (ie. racing in snow), I would stick with the stock tire sizes and adjust compound and tread for the conditions you ride in.

I think you'd not be far off with a Dunlop MX51 soft. If you want a little better wear out of it, go to a intermediate. The Dunlop's generally get favorable review's by a wide range of riders. But if you were out in the desert, Maxxis would be the tire of choice from what I hear.

Tire choice though is quite a personal thing, like oil brands. Just depends on what you like.

Jim.

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JCR runs MX51A 80/100 front and 739 Dez 110/100 rear.

I'm jus' sayin'...

and there's no harm in that!

But the main difference there is you have world class riders trying to wring every ounce of performance out of a machine and technique nor setup is an issue at all.

That's vastly different then the average rider throwing some rubber on for the next season or two and ridding everything from mud to hard pack.

Tire size does factor into cornering, but it's at the end of the list I think, once you have everything else in place; suspension, technique, and then compound for the conditions.

Jim.

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A taller, narrower rear tire will aid in cornering precision by a few percent.

That's why MX track bikes use 19" (really stiff side wall) and rarely bigger than 110.

As mentioned, proper suspension set up is vastly more influential.

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hi thanks for the help,

i have set my suspension and sag, and it is now perfect and does turn pretty well for a big heavy 450, but as big red is not a total a competition (extreme) enduro bike, every little thing i can do will hopefully make it a little bit more competitive and make my life a bit easier (i really wanted a 2 stroke honda, but honda won't make them will they !! there is a big market they are missing in europe, rant over)

I set the bars, levers, clutch biting point, dropped a tooth on the front sprocket for more bottom end power and all those things.

I have just retired road racing, and i am going to start doing some enduro races, and i am wanting to be competitive! and i know from road racing tyre choices are very important.

really appreciate the feedback

Edited by oatesy32

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Well your already beyond what I try to do with my bikes, so you'll need some wiser words then mine.

Good luck with the racing!

Jim.

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thank you jim, your advice has been useful, as has every ones !!

great site this !!

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and there's no harm in that!

But the main difference there is you have world class riders trying to wring every ounce of performance out of a machine and technique nor setup is an issue at all.

That's vastly different then the average rider throwing some rubber on for the next season or two and ridding everything from mud to hard pack.

Tire size does factor into cornering, but it's at the end of the list I think, once you have everything else in place; suspension, technique, and then compound for the conditions.

Jim.

True Dat!

So..then...

MX51FA frt in 80/100 or 90/90 or 90/100...& MX51 RR in 110/100.

There's your go everywhere-do everything tire set.

For those of you with a Maxxis Budget and want them to last? D952 110/100 RR and 80/100 Frt...I'd still opt for the MX51FA frt, tho...they work awesome and last suprisingly well...rememeber..."FA"...& we have all ended up on 80/100 frt after miles and miles and miles of testing from Baja to Clear Creek to Muddy Creek to Huntsville to So. Florida to Glen Helen...even Maui County, HI!

I'm jus' sayin'...

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A taller, narrower rear tire will aid in cornering precision by a few percent.

That's why MX track bikes use 19" (really stiff side wall) and rarely bigger than 110.

As mentioned, proper suspension set up is vastly more influential.

Yup, taller cross-section CAN mean less effort; but, you can usually count on more "Creep" and "Roll-Over", too...namely up-fornt.

Creep: Like when your Michelin Sand Tires want to CLIMB OUT of the Groove in a turn...

Roll-Over: When your tire actually folds over, side-ways; because, your tryin' to get away with lower pressures...etc.

This is how/why the 80/100 front came into existence.

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I love my Maxxis tires.. I usually run an s.i. model up front (80/100) and either the i.t. or desert i.t. in the rear, just depending on the type of riding I'm doing.

For the mountains and most riding I like the 110/100 but for long desert trips/races the 120/100 seems to track a little better and has more meat to resist pinch flats.

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