Alloy rims, WM2 or WM3 ??????

What you must remember is that Avon recommend a 2.5" rim for their 100/90 Roadriders, with the alternatives being 2.15" and 2.75". Then, in the model specific part, they recommend the same tyre for the standard 1.85" Commando rim. That is a very wide choice. However, the rim width recommended by them, to give the best fitted profile is 2.5". The Roadrider though, is not an old time classic tyre. It is one of their modern range with a V speed rating, not H as in most other suitable tyres. Not that we generally have to worry about tyres flying apart at high speeds on most of our Nortons.
Back in the 80's it was all the rage to fit the widest tyre you could on what were fairly skinny rims. Lots of 130 sections on 2.5" rims. For my McIntosh framed Suzuki , I chose a 3.5" (WM6) x 18 rear rim and a 2.75" x 18 front. At first, I ran Pirelli Phantoms with a 110/90 front. Steering was not what it could be. After consultation with a clever mate, I fitted a 100/90 Bridgestone Battlax H rated tyre suitable for 250/350 bikes. I was very sceptical until I rode it. Steering improved out of sight and I never had a grip problem.

Regarding the weight issue, Rich, the wheels fitted with the 2.5" alloy rims are noticably lighter than the standard wheels. The difference in weight between say, a 2.15" alloy rim and a 2.5" is probably negligable, especially as I use a non-shouldered rim profile. As I use the same tyres as I would on the standard rims there is no weight gain there either. I've read various articles where people have described Commando steering as anything up to "ponderous". I cannot reconcile this with my experiences. Mine is as light steering as you could want with no handling/steering issues at all. The wobble I got when I took my hands off the bars at about 40mph is barely there any more with no other changes.

What you must ask yourself is this, "do I want looks with a wider tyre with perceived advantages in regard to grip, or do I want to actually have better grip with more rubber on the road at any lean angle up to the maximum lean angle allowed by footpegs/stands with a proper rim/tyre combination?"

This argument is current even today with owners of modern sports bikes looking to fit the widest tyre on their rims. What they end up with is compromised steering with wider chicken strips because of their new, rounder profile. Go to a dealership and have a look at the new wide section tyres fitted to cruisers and suchlike. Then, stand behind the bike and check out the angle of lean of the bike at maximum lean. You will be surprised by the lack of available lean. A classic case of form over function, which is becoming so widespread these days. A perfect example is Harley's fitment of a six speed gearbox to their current models. Why would you have a torquey, low revving bike with a six speed box when it would be better served with a four speed ?
The answer is painfully obvious. Marketing.

This is confusing the living daylights out of me.
I have WM3 x 18" rims on mine. Recently had 100 x 90 on the front & 110 x 90 on the back & had handling problems over 80mph. Now put a 110 x 90 on the front & it is a lot better. I don't particularly like the feel of it though. It has been recommended to me to have 100 x 90 on the front & 120 x 80 on the back with a new rim. But, the same person said to use Bridgestones because Avons are funny handling on a Commando, yet he races with Avons, ?
Another famous person told me to sling the 18" rims & put 19" back on. Bloody Hell!
I still go round tight corners faster tha I do on my modern Bikes with huge tyres.
The best handling I have ever had is when it had 19" rims fitted with the original Mk1 Dunlop TT100s. Then they became discontinued.

Flo said:

This is confusing the living daylights out of me.
I have WM3 x 18" rims on mine. Recently had 100 x 90 on the front & 110 x 90 on the back & had handling problems over 80mph. Now put a 110 x 90 on the front & it is a lot better. I don't particularly like the feel of it though. It has been recommended to me to have 100 x 90 on the front & 120 x 80 on the back with a new rim. But, the same person said to use Bridgestones because Avons are funny handling on a Commando, yet he races with Avons, ?
Another famous person told me to sling the 18" rims & put 19" back on. Bloody Hell!
I still go round tight corners faster tha I do on my modern Bikes with huge tyres.
The best handling I have ever had is when it had 19" rims fitted with the original Mk1 Dunlop TT100s. Then they became discontinued.

Click to expand...

18" rear is OK but on the front it screws up the handling completely. Mine would go into a gentle weave by 70 and felt on the edge of a tankslapper if pushed up to 80.

I'm back on an 19" WM2 front,m 18" WM3 rear and very happy with it.

Here's a pretty good chart with all the specifications that you're likely to need. There are others on the web as well.

http://www.steelthundercc.com/tiresizes.html

Edited to add one more:

http://www.dropbears.com/u/utilities/tyrerim.htm

My mate Ben has a sign in his shop. It says,

"Your mate is my best friend. Ask him what you need and I'll sell it to you."

Flo, don't be confused. If you do your homework, it becomes clearer.

Flo said:

Another famous person told me to sling the 18" rims & put 19" back on.

Click to expand...

I may be psychotic, er...I mean psychic, but that would be Mick Hemmings? He's said it to me before.

Talking to my mate Ralph yesterday, he raves about the Dunlop TT100 GP, which, apparently is a race compound tyre. He has one on the front of his MK3 and says that the steering is fantastic. Doesn't last as long as anything else, but on the front, that wouldn't matter as you would still get a lot of life out of it.

Flo said:

I still go round tight corners faster tha I do on my modern Bikes with huge tyres.

Click to expand...

A very telling statement. As usual, not all is as it seems. Fashion dictates are somewhat more important these days than actual performance. See my comments on the cruisers with 8" rims and poor lean angles.

I am seriously considering the 100 x 90 front & 120 x 80 back. Has anybody got this combination?
I am waiting until about December to do some more work on the bike.
As for GTSUN's original question, maybe original size rims? Although it seems that 19" front & 18" rear seems good.
Correct for guessing who told me to go to 19" rims.
Also told me I shouldn't be using it hard, funny coming from someone who races them. Still like him though, & get most of my parts from him.

I run Dunlop GT 501, 100/90-19 front with a WM3. 120/90-18 rear with a WM4. I couldn't be more satisfied. If I were to change anything I'd go with a WM3-18 up front.

Everyone goes back to original design as an argument yet the Commando was designed with 19" rims front and rear, both WM2, the front tire was a 3.00 rib and the rear was the then new 4.10 lower profile tire. No change to the frame was made when they went to 4.10 tires on both ends and no mention was made of adverse handling from running the bigger tire on the front. Going to 18" rims on both ends with a slightly bigger tire on the back is probably closer to the original design of the bike, so don't worry and fit what you like, it is probably more important to get both wheels in line than any width and diameter of rims.

Jean

I couldn't agree more!

Well gentlemen (again used loosely ) I still haven't really got a good idea of what I want to do but for some reason I am a little adverse to going with the 18 inch rear. I still wonder how a set of WM3's x 19 front & rear would work with my Avon 100/90/19 tires. I may try this set up and see. As others here have said before about staying close to "stock" I too liked the way my 72 750 road with stock rims on Dunlop K81's in the 70's/80's and I can"t remember but think they were 410 x 90 x 19 or 110x90x19. I wish I could make up my mind because I want to drop them at Buchanons tomorrow. From a cosmetic stand point I don't like the look of commandos with wide rear tires on 18's but that's just me. I've always felt the same about the mid 70's Ducati 750 Super Sports. That back tire sure looks skinny and a little more width would be fine but to me it would not look right with a huge tire / small rim of modern type. I need to "pull the trigger" on this as a friend says so I hope I can come to a decision soon.

Your decision really depends on how you ride and what you want for looks.you already stated that you don't like the big rear tire look and have pretty much settled on the 19 F-R so it is now a matter of which width. If you want really quick turn in the WM2 with a 90-90-19 on front and a WM2 100-90-19 rear will accomplish this. A WM3 100-90-19 rear MIGHT slow down the handling a little. The WM3 front rear with 100-90 will definitely make it slower handling and I have seen some clearance issues on the front fender using a WM3-100-90 combination. I have the Excel standard profile WM2 aluminum rim's with 90-90=19 F 100-90-19 R and the thing I found with the change from steel to aluminum rims it REALLY made the turn faster so much so I had to relearn my turn in point's but I am a fairly aggressive rider in the mountains. I have not tried the flanged aluminum rim's but it should be quicker stearing the the steel rim's.

Thanks for your thoughts. A little quicker steering would be fine with me. I could be wrong but this 850 does not seem as nimbble as the 750's I had in the past but the tires could be at fault as they are a old, hard as rocks & not a matched pair. I never meant to use them it just took a while to get around to doing this. As for front clearance trouble, I am going to use a slightly smaller front fender with "Manx" type Y brackets so I already know I will need to replace the mounting "studs" with bottom head bolts as flush as I can get. Does any one know where I can get thoses? Or is it possible the threads will be easy to match. I will fit the fender after getting the rim/tire back on so I should be able to make room. Thanks again. Hey, Does any one have one of thoses old Lucas Rita oversize points covers that are flat on the front like the one on the picture of that motor in L.A.B's user ID photo? I have been looking for another one & would be willing to buy/trade? Thanks.

gtsun re read my post as there is an edit on rim size's.

850s also had 1 extra degree of head rake for stability, so that would make a difference as well.

This was a really informative thread. I am not going for a correct rebuild on my 71, but tire choices and handling are more important. I need to replace front rim so I may replace the rear while I am at it.