Big rear tires.


16 replies to this topic
  • heavyhitter

Posted October 03, 2007 - 12:22 PM

#1

I read alot of guys running fat rear tires on thier 650L's. I know the stock rim is 2.15 Most 110/100-18 call for a 2.15 rim. Most 120/90-18 call for a 2.50-2.75 rim.

Those 130's and 140's seem to be way to big for the rim they are going on. Some 140's call for a 3.50 rim! that over an inch larger than a stock rim.

Am I missing something here? :confused:

  • martinfan30

Posted October 03, 2007 - 12:51 PM

#2

dont know but i love my 130.

  • heavyhitter

Posted October 03, 2007 - 12:56 PM

#3

dont know but i love my 130.


Arent you running the 606's if I recall? Dunlop specifies a 3 inch rim :confused:

  • martinfan30

Posted October 03, 2007 - 12:58 PM

#4

mt21's

  • cleonard

Posted October 03, 2007 - 01:41 PM

#5

When you put a larger tire on a narrow rim, the bead gets sort of pinched. This bends the tire around a little more making the cross section more curved. On the pavement this can result in a smaller contact patch than a smaller tire. It will also wear more in the middle than a narrower tire. In the dirt this happens but to a smaller degree. In the soft stuff the extra width usually helps the most.

  • XR650L_Dave

Posted October 03, 2007 - 01:45 PM

#6

The 130 and 140 MT21s work great on the stock L rim.

The terrorflex 150 cheats by actually having a little 'ledge' that spaces the carcass out laterally from the rim.


Dave

  • AtomicGeo

Posted October 03, 2007 - 02:06 PM

#7

I just bought a 130/90 MT21 back tire for my 03 XRL ....fits fine. Looks cool & aggressive.

Geo

  • Rockjockey

Posted October 03, 2007 - 02:24 PM

#8

I run a Pirelli Scorpion AT 140/80-18 with no fitment problems at all.
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  • Sipes77

Posted October 03, 2007 - 09:28 PM

#9

I now have a Pirelli 130/90 - 18" MT21 on my stock '05 L,
I like it, I like it a lot!
Had to remove that plastic chain guard, because it was just barely rubbing on it.

  • heavyhitter

Posted October 04, 2007 - 05:47 AM

#10

This bends the tire around a little more making the cross section more curved. .


Yes this is what would concern me running a larger tire than is recommened for the rim. Fully aired up It would have to wear more than the tire that would actually be recommened for your rim. And running the correct size shoudl give you the same if not more tire patch on the ground. I know that airing the tire down would reverse the effect and give you more of a cross section and this would be great off road but would suck balls on road. It just seems like "stuffing 15lbs of potatoes in a 10lb sack".

Also I think that the side wall would suffer and be less ridgid. Because instead of being where it was designed to be structurally it is now moved x amount of degrees inward which would have to make the top edges of the tire flex more in an off camber situation and in a heavy lean in a turn. Im am sure this would be increased even more so by with a taller aspect ratio. Its just simple physics. Now how much of that is felt or effects the rider, Im not sure, but it has to be happening.

I know that a big beefy tire like a 140 will technically fit,but what is really going on with the intended geometry of the tire. I like a big tire as much as the next guy but I would feel better running it in rim much bigger than our meek 2.15 inchers. Hell I dont mind spandex either but I cringe when I see 350lb women in em. But in essence that what putting an oversized tire is doing. Mama Cass in spandex rolling around on your back wheel lol.

  • XR650L_Dave

Posted October 04, 2007 - 08:00 AM

#11

Yes this is what would concern me running a larger tire than is recommened for the rim. Fully aired up It would have to wear more than the tire that would actually be recommened for your rim. And running the correct size shoudl give you the same if not more tire patch on the ground. I know that airing the tire down would reverse the effect and give you more of a cross section and this would be great off road but would suck balls on road. It just seems like "stuffing 15lbs of potatoes in a 10lb sack".

Also I think that the side wall would suffer and be less ridgid. Because instead of being where it was designed to be structurally it is now moved x amount of degrees inward which would have to make the top edges of the tire flex more in an off camber situation and in a heavy lean in a turn. Im am sure this would be increased even more so by with a taller aspect ratio. Its just simple physics. Now how much of that is felt or effects the rider, Im not sure, but it has to be happening.

I know that a big beefy tire like a 140 will technically fit,but what is really going on with the intended geometry of the tire. I like a big tire as much as the next guy but I would feel better running it in rim much bigger than our meek 2.15 inchers. Hell I dont mind spandex either but I cringe when I see 350lb women in em. But in essence that what putting an oversized tire is doing. Mama Cass in spandex rolling around on your back wheel lol.




Its def. a tradeoff. If you see a lot of sand or mud, the drop in manners is worth the extra rear flotation.

The 140 MT21 seems quite happy on the skinny rim.

Dave

  • Rockjockey

Posted October 04, 2007 - 08:56 AM

#12

Yes this is what would concern me running a larger tire than is recommened for the rim. Fully aired up It would have to wear more than the tire that would actually be recommened for your rim. And running the correct size shoudl give you the same if not more tire patch on the ground. I know that airing the tire down would reverse the effect and give you more of a cross section and this would be great off road but would suck balls on road. It just seems like "stuffing 15lbs of potatoes in a 10lb sack".

Also I think that the side wall would suffer and be less ridgid. Because instead of being where it was designed to be structurally it is now moved x amount of degrees inward which would have to make the top edges of the tire flex more in an off camber situation and in a heavy lean in a turn. Im am sure this would be increased even more so by with a taller aspect ratio. Its just simple physics. Now how much of that is felt or effects the rider, Im not sure, but it has to be happening.

I know that a big beefy tire like a 140 will technically fit,but what is really going on with the intended geometry of the tire. I like a big tire as much as the next guy but I would feel better running it in rim much bigger than our meek 2.15 inchers. Hell I dont mind spandex either but I cringe when I see 350lb women in em. But in essence that what putting an oversized tire is doing. Mama Cass in spandex rolling around on your back wheel lol.


Agreed, but if the tire manufacturer suggests this as a possible application that will cause no ill effects, and you use it for street use, and keep it aired up properly, and buy your own tires it just comes back to the old different strokes for different folks addage.

  • ghrati ghoti

Posted October 04, 2007 - 09:20 AM

#13

The stock tire is a 4.60 or a 117, which puts it over the recommended rim size that was stated. Where are the rim recommendations from?

  • heavyhitter

Posted October 04, 2007 - 10:11 AM

#14

The stock tire is a 4.60 or a 117, which puts it over the recommended rim size that was stated. Where are the rim recommendations from?


The stock tires are 3.00-21 and 4.60-18
The stock rims are 1.60-21 and 2.15-18

You can get the recommended rim size from the tire manufaturer. 120 is the widested that most if not all manufatures would RECOMMEND, not saying a larger tire wont fit.

  • Shinyboat

Posted October 06, 2007 - 09:29 PM

#15

I run the 150 terraflex on the stock rim. It was definitely curved more when I put it on and wore in the center. After 180 miles, it has softened up a bit and more in the middle more and traction is incredible.

I have always run fatter tires than recommended. When the tire is fatter the middle wears faster and your best traction is after 25% wear. I also tend to run my tires till there is no more tread!

  • XR_Dude

Posted October 09, 2007 - 09:10 AM

#16

I run a terra Flex and love it! It lasts a long time and yes, it does seem to get better traction as it wears!

  • desert4seat

Posted October 09, 2007 - 02:33 PM

#17

Just completed a 200 mile ride (90% combination of snow, ice, mud, super soft sand…and 10% wet dirt).
For tires I used a 140/80 IRC M5B (before that was same tire but 130/80). In conditions like these, this tire worked beautifully! Super hook-up, and absolutely no complaints! I think The 130 turned a little better, but then again, maybe it didn’t.
Am I faster in the straights and slower in the turns on my 140? Who knows?

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Basically, on a dualsport ride when you’re running into a variety of terrain, I’m not sure tire selection (between a 120 or 140) is going to make that big of a difference. It’s a toss-up.

p.s. I could be wrong but my CR500R has the same size wheel as my L and calls for (stock I belive) a 140/80 18...
:confused:





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