Tires, How big can I go on My WR 450

I am looking at getting some new Maxxis IT's for My WR Do you suggest going wider if so how wide. It's been awhile since I had a bike [twenty years] so go easy on me. Thanks in advance

I am looking at getting some new Maxxis IT's for My WR Do you suggest going wider if so how wide. It's been awhile since I had a bike [twenty years] so go easy on me. Thanks in advance

I suggest that you hit Maxxis up and see what size IT tire is designed to your rim. If I am wrong here someone will catch it, but I think that the OEM WR wheels are 1.85-21 front and 2.15-18 rear. Every manufacturer seems to recommend a little different size tire for rim width...why... I dunno for sure.

I have the dunlop D606 in a 130/90

I have an 02 WR426 and am running the Maxxis IT 120. It's only one size up from stock which is a 110 and I have been very happy with it. The Maxxis seems to run close to the Dunlop sizes, but watch out for Michelin, they are a little different.

i been using irc m5b 140/80/18 for years, they fit and work pretty good

While ridding in Mexico, i have run as big as a 120 on my WR 426 and i have not had any problems with bogging or anything like that.

+ 1 on the Maxxis IT 120, it will fit nicely and is a brute in the desert:thumbsup:

Tire mfg's vary in sizes - Maxxis 120 = Michelin 140 :thumbsup:

Running the 952 120/90-18. No ill effects other than the tendancy to want to stand up mid corner under throttle. The 110 never did that. The added traction in most situations more than makes up for that little ill effect.

Running the 952 120/90-18. No ill effects other than the tendancy to want to stand up mid corner under throttle. The 110 never did that. The added traction in most situations more than makes up for that little ill effect.

Someone correct me if I am wrong...but a 130/80-18 and a 110/100-18 are (although different in aspect) roughly the same tire when fit to the same rim. If so then I think that the 140/80 (130/90) may be about the limit inside of these swingarms. I have never heard anyone running bigger than that (130/90 I have seen and is stretching it)...again I am not 100% here so chime in if I am talking out of the wrong end.

120mm X .9 =108 mm sidewall height

110mm X 1= 110mm sidewall height

130mm X .8= 104 mm sidewall height

140mm X .8=112 mm sidewall height

The 140/80 is the closest tire height wise to stock. Although the 120/90 that I'm running is 2 mm shorter than stock, the fact that the tread is 10 mm wider affected the handling the way it did (see post above.)

As you can see, the 130/80 is no where close to the same. I could only imagine how it would effect the handling of the bike being 20 mm wider than stock.

Converting Michelin tire sizes:

Michelin size 120/80x19 = 100/90x19 Conventional sizing

Michelin size 120/90x18 = 100/100x18 Conventional sizing

Michelin size 130/70x19 = 110/90x19 Conventional sizing

Michelin size 130/80x18 = 110/100x18 Conventional sizing

Michelin size 140/80x18 = 120/100x18 Conventional sizing

Michelin size 90/90x21 = 80/100x21 Conventional sizing

120mm X .9 =108 mm sidewall height

110mm X 1= 110mm sidewall height

130mm X .8= 104 mm sidewall height

140mm X .8=112 mm sidewall height

The 140/80 is the closest tire height wise to stock. Although the 120/90 that I'm running is 2 mm shorter than stock, the fact that the tread is 10 mm wider affected the handling the way it did (see post above.)

As you can see, the 130/80 is no where close to the same. I could only imagine how it would effect the handling of the bike being 20 mm wider than stock.

I noticed that speedracer found this info somewhere too....which, in conjunction with some reading, is why I am assuming that the different tires mounted on the same rim modify the footprint thus modifying the performance....Could it be said that a 120/90 vs a 120/80 on the same 2.15 inch rim would mean a wider footprint vs a more rounded footprint respectively?

tires120.jpg

My 130/90 is as big as I wanna go. The side lugs almost hit the chain. I think if the chain flexes a little bit, it's gonna hit the tire.

But I do feel the added traction from the tire. Tire spin has been reduced, but I have to watch how much throttle I grab so I don't pull a wheelie.

I'm running a IRC M5B 130/80-18 and love it. My conditions and riding style seen to necessitate it. Lots of loose stuff, everythings wet and muddy. Tons of fun. I've ran the stock tire down to nubs and tore chunks out of a small tera-flex (110/100-18, not the monster). I've been very happy with the performance of this tire and no problems with the rim size vs. the tire size.

Here's is the tire chart from IRC's website.

M5B : REAR

size - type - diameter - width - std rim - measurment rim

100/90-19 57M WT - - - -

110/80-14 53M WT 2.15 1.85

110/80-18 58M WT - - - -

110/90-19 62M WT - - - -

120/80-18 62M WT - - - -

130/80-18 66M WT 685 132 2.75 2.50

140/80-18 70M WT 691 139 2.75 2.50

So can I run a 120/80-19 on my wr426? 

42 minutes ago, Christian Jennings said:

So can I run a 120/80-19 on my wr426? 

You are responding to a 11 year old thread.

Your WR has an 18" wheel, not a 19"

You can run up to a 140 if you want to, but you have to go the tire manf's web site to see what the tire width acutally is.

Most of time rubbing occurs is because the chain is too short, pushing the rear wheel forward, and causing rubbing at the swingarm.

Thanks kran, someone was trying to sell me a brand-new 120/80-19 for $15 bucks didn't think it would fit but thought I would check. Guy was like " oh yah it'll fit trust me." Glad I checked with you guys. Thanks again!🍺

an YZ might have a 19 " rear rim...

which would fit on a WR....

But then I need to buy a new rim. I'll just stick with my 18" inch rim and tire.  Thanks for the info.

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