WM4.5 (2.75) sun rim: will it fit

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nonsense

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Another rim thread, sorry... I've read all the other tire/rim threads I could find, and didn't see this come up (at least not with an answer).

The question: would a WM4.5 (2.75") rim fit (a '74 commando) front AND back. The reason I ask is that I'm leaning towards Buchanan Sun rims, but these don't come in the recommended WM4 (2.5") size. I would be mounting Avon road riders, 18" back and 19" front, for which the recommended rim size is 2.5". I know WM4 rims do fit (see Fast Eddie and Fullauto 's posts in other threads) and that cNw offers a WM4.5 back WM3 front combo (although possibly only with a custom chain guard?), so mostly concerned with the WM4.5 in the front.

This would be with a stock fenders and chain guard.

Other options I am considering (all 18" back 19" front) are: Excel WM4 front and back, Excel WM4 back WM3 front, Sun WM4.5 back, WM3 front.

Not to continue arguments about which combo is best, any thoughts specifically regarding the handling of WM4 vs WM4.5 rims? WM4.5 (2.75") is within Avon's listed exceptable rim sizes and closer to the WM4 (2.5") spec then WM3 (2.15")...

Thanks.
 
On my ‘72 with stock WM2-19 and 100/90-19 Roadrider I have 1/8” clearance between tire sidewall and stock front fender brace.
 
ILLF8ED said:
On my ‘72 with stock WM2-19 and 100/90-19 Roadrider I have 1/8” clearance between tire sidewall and stock front fender brace.
Click to expand...
Would you mind also measuring the clearance to the fender it's self (or forks, whichever is closer)? If the fender brace is the only thing in the way I would not be opposed to modifying it or making one that went around the outside of the fender. I remember reading that WM4s fit with the stock fender and just needed low profile hardware, but that certainly seems a bit close.

madass140 said:
1/4" with 4:10 K81
Click to expand...
Do you know what rim that's on?
 
nonsense said:
Would you mind also measuring the clearance to the fender it's self (or forks, whichever is closer)? If the fender brace is the only thing in the way I would not be opposed to modifying it or making one that went around the outside of the fender. I remember reading that WM4s fit with the stock fender and just needed low profile hardware, but that certainly seems a bit close.


Do you know what rim that's on?
Click to expand...
Standard rim
 
A WM-4, 19" 2.5"rim, will fit a stock 850 Commando fender and clear. (Front and Back) I have these on my ride. Might not fit an early 750 fender as I haven't been able to verified that because I don't own that early a bike. Maybe others who have can comment.
Cheers,
Tom
 
nonsense said:
Would you mind also measuring the clearance to the fender it's self (or forks, whichever is closer)? If the fender brace is the only thing in the way I would not be opposed to modifying it or making one that went around the outside of the fender. I remember reading that WM4s fit with the stock fender and just needed low profile hardware, but that certainly seems a bit close.


Do you know what rim that's on?
Click to expand...
On my ‘72 with 100/90-19 Roadrider on WM2-19 rim tire space is 3/16” to the bridge stay and 5/16” to the fork leg.
 
Thanks all for the replies. It seems like a WM4.5 probably won't fit on the front. given how close a WM2 is I imagine the WM4 just barely clears.

My thoughts:
I'm more inclined to go with Avon's rec then a stock size (WM2) rim... maybe not if I was trying to use a original tire profile as well, but it doesn't make much sense (to me) to change to more modern tires without changing to more modern rims; they are designed to work together. Since Commandos were designed to run on same sized front and back wheel, the WM4 - WM4 combo makes more sense then the WM4 - WM3. Even though the WM4 - WM3 combo (with Avon tires) have close to the same rolling diameter, I imagine a WM4 - WM4 setup would maintain closer to original geometry when leaned over in a turn (eg. have a similar width) in addition to providing a close to same rolling diameter (not exactly the same as I want a 18" on the rear for more options in the future and a dedicated rear tire with deeper tread). I also have yet to hear anyone say a WM4 - WM3 is better then a WM4 - WM4, it just seems to be the more common choice due to clearance concerns and/or a result of trying to split the difference between originality and modern tires. I'm already going with modern tires on (black anodized, non-valanced) alloy rims, so I don't feel like I'm saving all that much originality by using WM3 modern alloy rims over WM4. I'm NOT saying WM3 or WM2 is wrong, just that it currently isn't the best option, given my priorities.

So... looking like I might go with Excel WM4s (18" back 19" front)

OK. does my thinking seem clear? I'm sure I forgot something...
 
ILLF8ED said:
I‘m not exactly clear with your goal regarding wide rims and fatter rear tire. Esthetics?
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Tire choice + the tires I have heard the best things about. I have repeatedly heard very good things (regarding handling, availability, grip, etc.) about Avon roadriders, with a second choice being Bridgestone BT45. Most if not all dedicated rear tires (which have a deeper tread then front or universal tires for longer life) are 18". Therefor I need to go to to 18" rear rims - I think a fairly common modification. Going with roadriders, 110/90 - 18, 4.00 - 18 or (less common) 120/80 - 18 are the sizes usually fit to commandos (that I have heard about anyway). According to Avon the recommended rim size for these tires is WM4, with an exceptable range from WM3 to WM4.5 or WM5 depending on the tire. Since I'm going to new rims regardless and will never want to go back to a 50yo tire profile I might as well go with Avon's recommendation, which should give the best tire profile. Bridgestone makes the same rec for BT45.

The front rim/tire follows similar logic: I want a roadrider, recommended rim size is WM4 (and see last post for why I'm leaning towards a WM4 vs WM3).

See https://www.avontyres.com/en-gb/tyres/roadrider-mkii (scroll down a bit) for the recommended rim sizes

TL;DR: I want Avon roadrider tires for their popularity/handeling, the tires are manufactured to work with WM4 rims.
 
TomU said:
Excell and Borrrani rims come in WM4-18. Avon and Bridgestone are both bias ply. Continental makes a radial ply

ContiClassicAttack: High-end radial tires for classic motorcycles

Exceptionally easy handling with ultra high grip and cornering stability. Superb control and optimum feedback. Excellent grip under all conditions, even in the wet and at low temperatures.
www.continental-tires.com www.continental-tires.com
Click to expand...
Hmm, something else to consider! Seems like WM4 front and back is the best choice either way.

As far as tire choice, if I already have a set of Avon Roadrunners (I think? they say AM20) that came with the bike and I mistakenly thought were Road riders until I realized the tread pattern was different a few minutes ago :rolleyes:, are they worth using or should I just get new tires (new roadriders or maybe ConiClassicsAttack). They are in decent condition, they were mounted but hardly used, and are still soft/no cracks or dry rot. Obviously not brand new, I can't find them on Avon's site in that size anymore. The front is 100/90H19 and the back is 110/90H18, so they would fit the WM4 rims I'll be getting. Maybe a topic for a new thread?
 
TomU said:
Excell and Borrrani rims come in WM4-18. Avon and Bridgestone are both bias ply. Continental makes a radial ply

ContiClassicAttack: High-end radial tires for classic motorcycles

Exceptionally easy handling with ultra high grip and cornering stability. Superb control and optimum feedback. Excellent grip under all conditions, even in the wet and at low temperatures.
www.continental-tires.com www.continental-tires.com
Click to expand...
After some quick research on radial vs bias ply... It sounds like radial is better, so why do so many people still use bias ply?
What I have found: There are occasional comments about specific tires having more or less grip, being better in wet conditions, or contact patch/stability comparisons, but I haven't seen much consistency (yet). Avon does have more of a reputation; compariable Continental offerings are newer as I understand it, which would explain why I have heard so much more about Roadriders/Avon. Roadriders are also slightly cheaper, but not so much that I wouldn't consider a ContiAttack if they really are better. I've also seen alot more tests/reviews (or opinions, depending on how you look at it;)) of different size roadriders on different size rims, so as of now I would feel more confident in saying roadriders will handle well without having actually tried them.
 
Unfortunately, i can't provide any guidance from experience. However, i've recently purchased Excel WM3-19 and WM4-18 rims and Continental Classic Attacks 100/90-19 and 110/90-18. Hope to have them mounted soon.

If the tires you have are good, that's an option. One thing to think about though is if they are closer to bad than good. Do you want to go through the aggrevation of changhing them out again.
 
I’d check the age of those tyres you have…

I do not believe Avon have made the AM20 series in those sizes for quite some time…

Given the time, effort and cost you’re putting into this, I’d stretch to new rubber if I were you.
 
Last edited:
Fast Eddie said:
I’d check the age of those tyres you have…

I do not believe Avon have made the AM20 series in those sizes for quite some time…

Given the time, effort and cost you’re putting into this, I’d stretch to new rubber if I were you.
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Well I'm certainly glad I checked, they're both from the 90s ! Guess I won't be using those. I'm tempted to go with Avon (vs Conti) just because of the reputation; they seem like a less risky option. Anyway I've got some time to decide, I've still gotta put the rest of the bike back together.
 
nonsense said:
Well I'm certainly glad I checked, they're both from the 90s ! Guess I won't be using those. I'm tempted to go with Avon (vs Conti) just because of the reputation; they seem like a less risky option. Anyway I've got some time to decide, I've still gotta put the rest of the bike back together.
Click to expand...
What did you ever decide, and how did it work out?
 

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