Tyre Selection 1974 commando

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Hi All,
Thank you all for your input. Wow, this is a far more complex question than I realised.
i reregistered my bike yesterday after a long lay up.
in fact I need both front and rear tyres. Unfortunately the almost unused tyres on the bike are about 12 years old and have some cracking on the sidewalls so I guess they have to go. I also understand that as the compound matures it loses grip.
in the past I always used either Dunlop K87 TT 100 4.10 19s front and back or Avon Road Runners 4.10 19s. I was happy with both tyres grip although my mileage was appalling, less than 2000km.
I had no idea about fitting a narrower tyre to the front. What does this achieve?
I will probably fit the K81 Dunlops as they maintain an original appearance.
I‘m very open to suggestions however but please keep it simple.
With thanks
Alan
 

Time Warp

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Its not complicated at all, you have all but two choices with stock 19 inch WM2 rims and if you went by the book the Avon would be removed leaving but one choice, the Dunlop based on its ability to fit the rim width being what I call an outrigger tyre. (sucked in at the bead area)

I would be fairly confident if you rolled up at the tyre shop they would grab either a Avon or Dunlop.
If you change the rims (19/18) that opens a few more doors but that costs plenty and that period look is gone (thankfully)
#
You could keep going.
Add some decent rims and tyres, what about the stock forks and bouncy old rear shocks, the swing arm bushes, the isolastics and so on.
Round and black does it for most folk.
 
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Which is why intelligent types (not I) fit a 18" rim so they can get dedicated rear tyres.
Instead I mindlessly get 3k per rear tyre. If you are energetic, you can move the fronts to the rear and the
new tyre to the front as if you don't the fronts never wear out just get to be life expired.
Those Intelligence types as you put it, do what tey do because 18inch rims have a wider tyre choice. I, myself, would only buy a bike if it would accept the TK17 rear tyre, cause I was doing 50, 000 miles a year, and as anybody will tell you , buying a new rear tyre every 5, ooo miles compared with one every 15,000 - no contest when it's your wallet that takes the hit.
 
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I had the Conti' Tour TK17 fitted to a Harley some years ago the mileage they gave was great but on a wet road they were like riding on ice! there needs to be a happy medium between wear and grip.
 

Fullauto

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Well, I don't wish to labour the point, oh, OK, I do, but several points are being missed here by well intentioned and intelligent people with many miles of Commando riding experience. The first is that (according to Avon ) their 100/90 x 19 Roadriders are made for a 2.5 inch rim, two sizes bigger than the standard Norton rim. When I looked at this originally I thought, well, they made the tyres, they should know, so I had 2.5 inch alloy rims laced up to the hubs with, after trying various combinations, Avon Roadriders at both ends in 100/90 x 19. Now, they have listed other "acceptable" rim sizes, but they are not ideal. As the rear wears out, the new tyre gets fitted to the front and the old front goes to the rear. The result? The best handling bike I've ever owned, or ridden, with acceptable tyre life and none of the funny little Commando quirks that everybody lives with and just writes off as being "just a Commando trait". The fluttering handlebars at 40mph, the strange handling when the tyres get towards the end vof vtheir working life etc. My knowledge comes from trying these things, and not saying "I would think" or some such other crap which you see on this forum. Actual experience. At high speeds, Commandos can exhibit heavy steering or a reluctance to turn in to a corner. Not mine. Light at all speeds. A Dcati riding friend of mine rode it and claimed it was too skittish and wanted to run ioff the road. He rides bevel drive Ducatis which have extremely slow steering. My bike is just as stable but will run rings around a bevel drive, He was mistaking the quick steering for instability. I always laugh when I see a Norton with a steering damper. It's the last thing a Norton needs.
Someone in this discussion also labours the point about tyre life, or, more to the point, lack of it. Now, this bloke has said before that he only does 1000 miles a year, mainly on the racetrack. Huh? So how is tyre life even an issue in this context ?

Tyre profiles. The rim width also affects the tyre's profile. Look at a 100/90 Avon Roadrider fitted to a standard Commando rim. Look at the lean angle you would have to achieve to reach the edge of the tyre's useful tread. It just can't be done. So, on a smaller rim, you simply CANNOT get to the edge of the tyre. On a 2.5 inch rim, no problem. ALL of the tyre is useable.

So please, try to refute my findings using actual experience and measurement, but please, no "I would think" arguments.
 
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So
Well, I don't wish to labour the point, oh, OK, I do, but several points are being missed here by well intentioned and intelligent people with many miles of Commando riding experience. The first is that (according to Avon ) their 100/90 x 19 Roadriders are made for a 2.5 inch rim, two sizes bigger than the standard Norton rim. When I looked at this originally I thought, well, they made the tyres, they should know, so I had 2.5 inch alloy rims laced up to the hubs with, after trying various combinations, Avon Roadriders at both ends in 100/90 x 19. Now, they have listed other "acceptable" rim sizes, but they are not ideal. As the rear wears out, the new tyre gets fitted to the front and the old front goes to the rear. The result? The best handling bike I've ever owned, or ridden, with acceptable tyre life and none of the funny little Commando quirks that everybody lives with and just writes off as being "just a Commando trait". The fluttering handlebars at 40mph, the strange handling when the tyres get towards the end vof vtheir working life etc. My knowledge comes from trying these things, and not saying "I would think" or some such other crap which you see on this forum. Actual experience. At high speeds, Commandos can exhibit heavy steering or a reluctance to turn in to a corner. Not mine. Light at all speeds. A Dcati riding friend of mine rode it and claimed it was too skittish and wanted to run ioff the road. He rides bevel drive Ducatis which have extremely slow steering. My bike is just as stable but will run rings around a bevel drive, He was mistaking the quick steering for instability. I always laugh when I see a Norton with a steering damper. It's the last thing a Norton needs.
Someone in this discussion also labours the point about tyre life, or, more to the point, lack of it. Now, this bloke has said before that he only does 1000 miles a year, mainly on the racetrack. Huh? So how is tyre life even an issue in this context ?

Tyre profiles. The rim width also affects the tyre's profile. Look at a 100/90 Avon Roadrider fitted to a standard Commando rim. Look at the lean angle you would have to achieve to reach the edge of the tyre's useful tread. It just can't be done. So, on a smaller rim, you simply CANNOT get to the edge of the tyre. On a 2.5 inch rim, no problem. ALL of the tyre is useable.

So please, try to refute my findings using actual experience and measurement, but please, no "I would think" arguments.
so, what is the rim width of a standard Commando? I see that Avon recommended a rim width from 2.15 to 2.75 for their 100 90 19
al
 

Fast Eddie

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Fullauto is correct in that Avon Roadriders are stated as requiring a wider rim than Norton’s have as standard.

Someone on here once posted info from Avon contradicting that and saying it was ok to use the narrower rims. And many have done so and don’t report any issues.

Nevertheless, Avon have not updated their web site, and when I tried typing in Norton Commando into their search function it did NOT show up the 100/90 19s (as it used to).

So, if in doubt or unhappy about this (as I would be), and wanting to keep the stock rims, you are probably best sticking to the Dunlop’s or possibly Avon Road Runners (AM9s), which according to Avon have a minimum rim width requirement of 1.85 inches, IMHO.

If you’re changing rims it’s a different matter and Avon provide better info on this than many tyre manufactures. I did similar to Fullauto and went with 2.5 inch rims front and rear and like him I find the handling to be excellent and very confidence inspiring. The wider rim does give the tyre the correct profile, this maximises the tyre contact patch at all lean angles. I dislike changing tyres more than he does though, so went with the 18 rear.
 
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Time Warp

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So

so, what is the rim width of a standard Commando? I see that Avon recommended a rim width from 2.15 to 2.75 for their 100 90 19
al

WM2 - 1.85" which is why I said way back you are pretty much stuck with the Dunlops (even though there are 1000's of Commando's with Avons fitted)

"Its not complicated at all, you have all but two choices with stock 19 inch WM2 rims and if you went by the book the Avon would be removed leaving but one choice, the Dunlop based on its ability to fit the rim width being what I call an outrigger tyre. (sucked in at the bead area)"
 
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Time Warp

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I now wonder what the Kiwi dude (John F) is using on his 'Round the World Commando.

Edit.
Mitas it seems.
 
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Fast Eddie

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WM2 - 1.85" which is why I said way back you are pretty much stuck with the Dunlops (even though there are 1000's of Commando's with Avons fitted)

"Its not complicated at all, you have all but two choices with stock 19 inch WM2 rims and if you went by the book the Avon would be removed leaving but one choice, the Dunlop based on its ability to fit the rim width being what I call an outrigger tyre. (sucked in at the bead area)"

If someone dropped the coin for wider quality alloy rims/spokes (around AU$1164 + $300 if you got them laced) and went to a 18" rear you would hardly fit those dirty old cross ply Avons when that would open up plenty of other tyre options.
Almost. There are still the Road Runners to consider too.

I looked into the various modern radial options recommended by some, I’m sure they’re good, but for me the Roadriders are so good I’m reluctant to try out alternatives !
 
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I now wonder what the Kiwi dude (John F) is using on his 'Round the World Commando.

As A former NZ M/C Shop owner & experienced racer I am fairly sure he will be up with the play.
 
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I still use K81s, and after having a 3.60 on the front seeming to promote the 'Commando Weave' I switched back to a 4.10 which definitely calmed things down.
The only issue with the TT100s is their very marked tendency to tramline over irregularities in the road. I'm assuming it's the combination of the open tread pattern and modern soft tyre compound. The grip is great, and I'm used to the slight squirrely behaviour... makes me feel like I'm really taming the thing, you know?
The mileage on rears isn't great though. I think I got around 2k out of the last one, but I have been known to be a bit naughty on occasion...
I like period-correct looking rubber on original looking bikes, and my '70 Roadster has a 3.00 ribbed on the front which makes it handle like a 250!
Otherwise Roadriders are good, and available in track compounds.
 

robs ss

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On my cNw 850 Matt fitted Bridgestone BT45s
* 120/90 18 M/C 65V rear
* 100/90 19 M/C 57V front
I have found them to be good with no problems so far. I have taken them to 125mph without issue.
Very limited wet weather experience (I have a car!)
A bit over 4000 miles and the rear is a bit over half worn - the front, understandably, much less.
They don't make them any more, but I'll be fitting their successor, the BT46 which, I have confirmed with Bridgestone, have all the same dimensions.
 
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robs ss

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... but for me the Roadriders are so good I’m reluctant to try out alternatives !
The Roadriders have a very similar look, profile and tread pattern-wise, to the Bridgestone BT45 (&46). I wonder what the difference in performance(s) is?
 
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Continental do.

100/90/19 fronts.
100/90/19 and 110/85/19 rears plus a 120/90/18.

All are radials but not suited to the stock rim widths.
#


The OP is pretty much stuck with the tyres mentioned in previous posts if stock WM2 rims.
I'm wary of putting any Continental tyre on the front rim - why? No grip. IMO
I put the gripest tyre I could lay my hands on the front, everytime.
 
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I had the Conti' Tour TK17 fitted to a Harley some years ago the mileage they gave was great but on a wet road they were like riding on ice! there needs to be a happy medium between wear and grip.
Yes, you can't have an hard wearing tyre if you want grip. I think I figured that out a long time ago.
 
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The only issue with the TT100s is their very marked tendency to tramline over irregularities in the road. I'm assuming it's the combination of the open tread pattern and modern soft tyre compound.
I dumped my TT100's for the white lining within 2 weeks of buying the bike in 1988, so doubt it has anything to do with modern compounds. They were not worn either.
 

Fast Eddie

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The Roadriders have a very similar look, profile and tread pattern-wise, to the Bridgestone BT45 (&46). I wonder what the difference in performance(s) is?
I have no idea!
You’d have to do back to back tests on the same bike to be clear about that. Certainly not something I fancy doing !
 
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