Early Commando Tires

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sidreilley

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:roll: I've just begun looking around for some new tires for my 69 and it's been somewhat of a surprise. I didn't realize that they came with such small tires (that's not what's on it now)! I've read that the fronts should be 3.60x19 up to 1970 and then on 71 and newer the yokes were changed to allow the use of 4.10x19, which are much easier to find. The idea of the same size on both ends is very attractive but I don't want to spoil the handling. What is the consensus of opinion on the matter among those who know?
cheers,
 
Actually, the first Commandos used a 3.00 X 19 ribbed front tire and the then new 4.10 X 19 rear, both were Avons which we dubbed "savons" (in french savon = soap) because they slipped quite a bit. The fact the Avons slipped saved my gearbox from a lot of harm. When I fitted the hot Dunlops TT100s, I broke the transmission casing twice, the main shaft and the layshaft and these were all separate incidents. And I will not admit to any abuse of the bike :twisted:

Jean
 
sidreilley said:
I've read that the fronts should be 3.60x19 up to 1970 and then on 71 and newer the yokes were changed to allow the use of 4.10x19, which are much easier to find. The idea of the same size on both ends is very attractive but I don't want to spoil the handling.
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All Commando yokes are 7-3/8" between centres.

You can use either 3.60 or 4.10 on the front (provided there's enough mudguard/fender clearance?). The 3.60 will give slightly quicker steering.
 
The front mudguard and stays were narrower until 1971. There is a narrow chrome fender, a wide chrome fender, and a wide stainless fender. A 4.10H-19 front tire will not fit the early narrow chrome fender on your "S".

Also the 3.60H-19 Dunlop K81 is not sold in the US. It is sometimes possible to get them from Canada. If you wish to run Avon AM26's, a 90/90-19 front will fit the small fender. I'm not sure if the 100/90-19 will clear the stays.

If it were me, I'd go with th 90/90-19 AM26 front with a 100/90-19 AM26 rear. They are much better than the vintage Avons these guys are talking about.
 
I've never experienced anything other than Dunlop 3.60 and 4.10X19's on a Commando. I thought that provided predictable control while cornering under power even if the back-end broke lose due to loss of traction. It never 'hooked-up' in a manner that would lead to a 'high-side' but I'm curious what might be expected with modern rubber compounds. Are they better or worse. IMHO unpredictable is pretty much unacceptable. Especially as I get older.....falling off isn't as easy to bounce back from. :p
 
I never had problems with the original Avon 300 19 SM on the front and the 350 19 Safety on the rear, but then I was using the bike as a touring bike, not a racer, but it went up and down the road from Sperryville to Luray just fine. I have no experience with the Dunlops other than my belly has dunlopped over my belt.

Dave
69 'S' project
 
The main problem I found with trying to put the 3.60 tire on the front was that no one seems to have any! The idea of a new Avon AM 26 90/90x19 looks better all the time. Would there be a down-side to using the same thing on the rear? I put a set of AM26's on my new Bonneville a couple of months ago and they were a huge improvement so I know it's a good tire, but I thought it might be better to go with an original fitment here. When you combine the evolution of tire sizes and profiles since 1969 with what's really available now, it becomes a bit confusing. After reading thru the recent thread on rim sizes I started thinking about the whole tire size/profile evolution thing. I was hoping someone out there had gone round this buoy before could tell me what they were running that works and where they got it.
 
The idea of a new Avon AM 26 90/90x19 looks better all the time. Would there be a down-side to using the same thing on the rear?
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The 100/90-19 AM26 is the only 19 inch size recommended by Avon for rear fitment. It is probably just a marketing and CYA thing, but if you do use the 90/90X19 on the rear be sure to install it in the opposite rotation as indicated for the front.

There would also be a slight error incurred on the speedometer, but if your Smiths instrument is like mine, it will be well within its built in error.

The last 3.60H-19 K81 Dunlop I bought came from Mike Partridge at Walridge Motors.
 
Don't put a 4.10 TT100 on the front of a Commando--or any brit bike for that matter. I fitted a 100/90/19 TT100GP in place of a 4.10, and it made the handling much sharper. Stickier compound than a regular TT100, so it will wear quicker, but who ever wears out the front tyre on a Commando--they just go hard, eventually. And the tread pattern is identical, so it's a cosmetic match. size is 10mm lower and narrower than a 4.10. Availability? Still in the Dunlop catalogue in Australia, mostly sold to the classic racing crowd.
 
I use Avon AM26 Roadriders on both ends in 100/90 19. When the rear wears out, the new tyre goes on the front and the front tyre goes to the rear. You never have to replace both at once.
Who wears tyres out on their Norton, Ralph? Me. Between my Buell X1 and my 850 I have bought 27 new tyres in just over three years. Ask me about tyres.
 
Oops. Just read the original post. Use the 100/90 on the rear and the 90/90 on the front. Should work a treat.
 
Fullauto said:
Oops. Just read the original post. Use the 100/90 on the rear and the 90/90 on the front. Should work a treat.
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I just switched to Roadriders dfrom Continentals the Roadriders ar superb wet and dry no more whitelining...
 
After more searching, I found an Avon AM26 front in 3.25x19 and that seemed closest to the original spec. Combined with an AM26 100/90 for the rear, the cost from Denis Kirk was less then the cost of a single Dunlop TT100 that I found in the correct size for the front! Full Auto, I really like your idea of using the same size on both ends and swapping the front to the back an putting a new one on the front.
 
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