Michelin Tire - what size?

[ChuckyBoy]

After reading many personal opinions on which tire is best, I have decided on a Michelin M12 for the rear of my 1998 KDX 220.

The only problem is that I don't know which size to order. I currently have a Dunlop 756 100/100-18. Michlein does not make a 100/100 in the M12. The M12 on comes in these 18 inch sizes -

130/80-18
120/90-18

Will one of these fit on my bike?

Also, here's a dumb question...what do those numbers mean anyhow? I think it's a ratio or proprotion...side wall to width?

Thanks in advance for you help,
Chuck

 

[Fred T]

120-90/18

 

[weaselcircus]

Here's a chart that was done to help with picking the right Michelin tire: http://www.accwhse.com/zmicheli.htm

Scroll down to the "Michelin Mounting Chart" section.

 

[Farmer John]

There are a couple of ways to measure a tire. The two that you have referenced are quite similar. The way Michelin does it has been around since the mid 70's. The measure the tread (120mm), then determine the percentage of the side wall vs the width (90%), & then add the rim size to get a 120/90X18. Dunlop started with the "new norm" in the early to mid 80's (remember K595's?). They measure the width of the carcass, pre-tread, (100mm) then determine the percentage of sidewall vs width (100%), & then add the rim size to get a 100/100X18.

It can be confusing since most manufactures use both systems, but when dealing with off road tires there is a simple rule of thumb: 19" tire with /90 is a carcass measured tire while /70 or /80 is a tread measured tire, 18" tire with a /100 is a carcass measured tire & /90 or /80 is a tread measured tire.

120/90X18 = 100/100X18 = 4.00X18
130/80X18 = 110/100X18 = 4.50X18
140/80X18 = 120/100X18 = 5.10X18

120/80X19 = 100/90X19
130/70X19 = 110/90X19
140/70X19 = 120/90X19

Now many "nitpickers" will be quick to point out that the math doesn't always convert. So what, it's how the Dunlops, Michelins, Metzeler/Pirellies, etc make em.

 

[Farmer John]

weaselcircus,

good link!

Boy, I had forgotten about the wonderful world of "alpha" sizes. I used to know alpha to WM rim sizing by heart, but thankfully the 70's are gone. ;)

wait, WM3 can take a MT or MU 90.... :think:

 

[canyncarvr]

I used the 130-80 on my bike. The more grip the better. Fit wasn't a problem.

Well...that WAS an S12. I imagine the sizes of the two types are at least similar if not the same.

 

[CMcCarthy]

I concur with CC. I also run a 130 S12 on my KDX. It fits great and works great too.

 

[ChuckyBoy]

Thanks guys for all of your input. I hate to appear like an imbicile but sometimes what's totally plain to see to everyone else, is completely Greek to me. Little by little, with y'alls help, I am becoming more educated about this obsession we have. Thanks.

Farmer John...thanks for taking the time to type up the chart of relative tire sizes. After reading it I had one of those "light bulb" moments.

Weasel...excellent link. I think I could have surfed the web all day and never found that. Thanks.

Happy Holidays,
Chuck

 

[canyncarvr]

More of the same....sorta. This chart shows the relationship between 'old' and 'new' tire sizes as FJ noted. In a bit different format.


From:
http://www.motorcycle-karttires.com/charts/knobby.asp

 

[ChuckyBoy]

A rhetorical question...Where to you guys find this stuff!

It amazes me...the wealth of knowledge that you guys have!

Thanks to Al Gore for inventing the internet! Otherwise, that wealth of informtion would go largely untapped.

I truly appreciate all of y'alls help.

Chuck

 

[canyncarvr]

I'd like to say I invented the internet or some other bogus BS that would infer I was brainy and know a bunch-o-stuff.

But....I just USE algore's invention to find most of it. Google is a great search engine these days (google.com). Yahoo used to be. I'd saved the link with the above chart sometime ago from a google search for something like 'motorcycle tire size'.

Quite often you get more useless junk than you can shake a stick at...sometimes you luck out.

 

[Randy M.]

I'm picking up my s-12's tomorrow, 130 on rear and 90/90 on front.

 

[D36-108A]

Hmm, I thought I ran 120 Michelins on my KDX... you sure 130 is right? Even though you can fit a slightyly wider tire, it does weird things to the shape and may not be ideal. And it's heavier.

 

[Fred T]

I guess rear tire size is a personal thing. I would NEVER put a 130 on the back of my KDX, sucks too much power in the sandy conditions and eliminates steering with the rear tire all together. I suppose though if you ride in shaded wooded, wet snotty clay all the time then traction pretty much sucks and bigger is better. Just not for me. I ran the s 12 120 on my highly modded 220 and it was perfect.

I run a 130 on my wicked fast KTM 250 EX/C and that is perfect for that bike.

My winter spikes are also M12 130's and I'll know about those puppys after this Sunday. :aj: