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hawaiidirtrider

Who runs a wider rear rim for offroad?

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Just wondering.. Earlier it seemed like few even heard of running a wider rear rim currently. It’s an old school mod that few even talk about. Just wondering how it works for them and what kind of bike and tire and what kind of terrain. Vintage mx guys might be familiar with this too.

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140 tires catch knobs on the chain and rip off. A 215 rear rim (size that is stock on most 250+ smokers and 350+ thumpers) is more than adequate for a 130. I prefer to run a 120 width.

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Stock rim, and a 110/100 profile. Wide is not always good, unless you like going straight. Wider does not mean more traction. 

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I've experimented with varied tire profiles on a number of machines. Once you start changing the consistent radius of a tire, you get ill handling bikes. 

 

Years ago when i did some superbike track days a bunch of people were replacing the 180/55/17 rear tires with 190 and 200 wide rubber. Thinking more contact patch meant more traction. On machines with 150-160HP hitting upwards of 170mph every bit helps. However the wider profile only helped in straight line conditions, once you started leaning over on the edge of the tire you had no more traction than before, and it had terrible manners wanting to stand up on you when you wanted to lean in. Same influence happens on a dirt tire, so keeping with stock radius will keep lean in feel the most neutral. 

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3 hours ago, redhurricane said:

Stock rim, and a 110/100 profile. Wide is not always good, unless you like going straight. Wider does not mean more traction. 

Sure wider gives a bigger footprint and does give more traction. Of course it’s different from a skinnier to a wider rim and the bikes do great not only going straight. If you’ve ridden a variety of wheel setups wide and also size of wheels you will know there’s a difference like even 17” vs 18” rim too. Old school 80’s mx bikes run 2.75” width rim and 18”. My original 82’ Husky 430 came from factory with a 17” wheel and had a 5.10 tire on it. Other bikes came with wider rims aswell.   My Father has been a wheel guy making wheels for shops and friends with a wide variety of motorcycles on and off road. He’s made tons of different width setups for 60 years or so. He’s made a bunch of wider rear dirt wheels as it’s been a common mod for local riders for years.  It’s not as popular now as more have just forgotten it seems. There are better hybrid tires and guys run trials tires and didn’t before. My 82’ 430 cr Husky right now has an “upgraded” tricker vintage mx mod going from a 17” rim to an 18” rear rim with a 2.75”width rim. In that case a wider variety of tire choices is a benefit too.  There are options for ordering a 2.5” rear rim when ordering a wheelset from dubya or whatever. Some years ago Taddy had a 2.5” rear wheel on his endurocross ktm 300. He had his footpegs moved rearward a little too if  I remember right. Anyway a wider rear rim was a common mod for offroad dirt riders but I guess it’s more off the radar now . My Dad wasn’t the only guy making wider rims. It was common enough for those who wanted an edge for traction and riding.

Edited by hawaiidirtrider

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24 minutes ago, redhurricane said:

I've experimented with varied tire profiles on a number of machines. Once you start changing the consistent radius of a tire, you get ill handling bikes. 

 

Years ago when i did some superbike track days a bunch of people were replacing the 180/55/17 rear tires with 190 and 200 wide rubber. Thinking more contact patch meant more traction. On machines with 150-160HP hitting upwards of 170mph every bit helps. However the wider profile only helped in straight line conditions, once you started leaning over on the edge of the tire you had no more traction than before, and it had terrible manners wanting to stand up on you when you wanted to lean in. Same influence happens on a dirt tire, so keeping with stock radius will keep lean in feel the most neutral. 

I think you need to for ex try a 2.5” width 18” rim on your dirtbikes... just to see. There’s no ill handling. It’s different for different situations a bit but I wouldn’t go through the trouble, time and money if there wasn’t a worthwhile benefit. 

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I've experimented with varied tire profiles on a number of machines. Once you start changing the consistent radius of a tire, you get ill handling bikes. 
 
Years ago when i did some superbike track days a bunch of people were replacing the 180/55/17 rear tires with 190 and 200 wide rubber. Thinking more contact patch meant more traction. On machines with 150-160HP hitting upwards of 170mph every bit helps. However the wider profile only helped in straight line conditions, once you started leaning over on the edge of the tire you had no more traction than before, and it had terrible manners wanting to stand up on you when you wanted to lean in. Same influence happens on a dirt tire, so keeping with stock radius will keep lean in feel the most neutral. 


Exactly
Tires are designed and manufactured by very very smart people. And in the last few years with the advent of Hybrid tires they are designed for a certain sized rim to do their job as efficient as possible.
Seems to me one of the most important things we should be concerned about is tire pressures and how to attain them to get the maximum adhesion and stability. Second is the size of the carcass, as IMHO these two things have to work in unison with how we adjust our suspension for what we expect out of our bikes
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With the wide variety of hybrid trials/ knobby tires these days I have toyed with having 2 rear wheels to compare a regular 18” 2.15 width rear rim with a trials tire and comparing with an 18” 2.5” width reat rim with a knobby 120 or 140 tire just to see how both compare. Maybe an IBEX 120 or a Shinko 505 120 rear knobby are good tires . I never got to use those type tires as those weren’t available. The good tire before has been a big Pirelli MT16 as that was the old go to tire in the past. Itworked great with that tire. I figure with the improved rubber compounds of newer hybrid tires it should be better. I didn’t change to a wider rim for my 300 rr yet. When I do put that 2.5” width I’ll show and give a report. I’m wondering if changing gearing might be a factor too later. 

Actually I have my 12’ 350 race stock width rear rim with an almost new equilibrium tire that ai could possibly switch out on my 300 rr to compare with later. I know an equilibrium isn’t the same as a trials tire though. I hope the 12’ 350 and 15’ 300 rr are interchangeable. Maybe just spacers different?  

Edited by hawaiidirtrider

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14 minutes ago, Mark-us-B said:

 


Exactly
Tires are designed and manufactured by very very smart people. And in the last few years with the advent of Hybrid tires they are designed for a certain sized rim to do their job as efficient as possible.
Seems to me one of the most important things we should be concerned about is tire pressures and how to attain them to get the maximum adhesion and stability. Second is the size of the carcass, as IMHO these two things have to work in unison with how we adjust our suspension for what we expect out of our bikes

 

Yea.. and there’s always room for innovation.. even old school mods. It will be interesting to see how the different knobbie tires work. A regular intermediate big rear knob tire could possibly even work best. The MT16 is an intermediate tire. It’s been a great tire for a wide variety of use.. mx to hare scrambles and hard enduro. It’s a wait and see thing. 

I am actually surprised there aren’t more that are familiar with wider rim for offroad riding. Lots of vet riders are familiar here. I thought more were familiar. A friend that rides with us that was living in Oregon has a 2.5” 18” rear wheel on his yz 250 set up for trail. I just thought wider rims behind was more common of a mod than what’s been shown on this thread so far. 

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Just for reference here’s my cr 250 with a 2.5” rear rim . Just to see since this seems to be a more rare mod these days. 

Thats some thick Buchanan stainless spokes and the stock hubs were chromed. It looks nice and it’s easier to clean. 

 

DD4941FB-8060-4441-B0F4-EF3836812E1A.jpeg

Edited by hawaiidirtrider

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2 minutes ago, hawaiidirtrider said:

Just for reference here’s my cr 250 with a 2.5” rear rim . Just to see since this seems to be a more rare mod these days. 

 

DD4941FB-8060-4441-B0F4-EF3836812E1A.jpeg

Thats a 01 huh, man i want one of those 😔

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7 minutes ago, Mr221 said:

Thats a 01 huh, man i want one of those 😔

Yea I sold to a friend of a friend and he put an eric gorr 300 top end on it. I hurt my knee and decided I needed estart for my 2 stroke.I got a 300 rr Beta. I’m going to put a 2.5” rear rim on it . I’ve been procrastinating. I rather go ride than change the wheels out. I just put together the front wheel with stainless spokes.. now gotta do the back. I loved that Honda but the transition to a Beta is great. Handling seems like a Honda to me. 

I had the honda from almost new so I was clear about what upgrades I wanted.. 6 speed, estart and 50 more cc was a good addition.

Edited by hawaiidirtrider

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5 minutes ago, hawaiidirtrider said:

Yea I sold to a friend of a friend and he put an eric gorr 300 top end on it. I hurt my knee and decided I needed estart for my 2 stroke.I got a 300 rr Beta. I’m going to put a 2.5” rear rim on it . I’ve been procrastinating. I rather go ride than change the wheels out. I just put together the front wheel with stainless spokes.. now gotta do the back. I loved that Honda but the transition to a Beta is great. Handling seems like a Honda to me. 

I bet the beta is fun, one day i was like im going to build a 250 and i went out and found a cheap 2000 yz250 tore everything down bottom end top end oem crank oem piston v force reeds and a carb off a 15 husky 250 man i thought that thing ran good untill my buddy pulled his bone stock 01 cr250 and we did a long pull to a semi long hill climb and mind you i smoke his ass any day of the week plus hees a big boy 250 im roughly 180. My bike was jetted perfectly and running mint and he walked away from me on the 01, i wanted one since, he lets me ride here and there i never want to give it back😂

 

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On 1/9/2019 at 6:16 AM, woods-rider said:

140 tires catch knobs on the chain and rip off. A 215 rear rim (size that is stock on most 250+ smokers and 350+ thumpers) is more than adequate for a 130. I prefer to run a 120 width.

That’s never happened on any 140 tires Ive run.. What bike has that happened with and what tire??

On that cr 250 pictured with the 2.5” rear rim I put just about the largest available rear tire in a 140 M5B tire behind and it cleared just fine with the chain. It rubbed the wr yammie radiator overflow tank I put on  a little but it still was fine. As large as that tire is the compound didn’t work as well as the MT16 though . I changed it back. 

 

Edited by hawaiidirtrider

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That’s never happened on any 140 tires Ive run.. What bike has that happened with and what tire??


2006 and 2012 WR450F. I don’t recall the exact tires I used in 140s since it’s been a few years, but I have tried multiple 140s and they all seemed to have the same issue for me.
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