Tyre selection

My first Commando was a '69 Fastback (bought second hand fromits first owner in '72) and whichhad a 3.00 x 19 ribbed front with3.50 x 19 rear (TT100 or Avon Roadrunner , as I recall). Handled like a dream.

I would stick to the standard sizes after experiencing undesirable characteristics on my 1975 Mk3 when I changed to 18" rims. 19" rims are back on now with Avon Roadriders. Give Avon a call 01225703101 and they'll give you tyre sizes which, in their opinion, best suit your bike. Don't worry about the tyres relatively small width. I guess there wont be much difference, if any, from what the racers were using back in the 1970's, and todays road tyres are probably comparable if not better than the period race tyres.

I use a 3.00 x 19 Avon Speedmaster on the front and a 3.50 x 19 Avon Grand Prix on the back on my 1959 S Type. These are the tyres specified by Norton for these bikes. It was later when 4.10 x 19 were fitted front and rear. The only advantage to the 4.10 set up is that when the rear tyre wears out, you fit a new one on the front and put the old front one on the back.

I like the tyres I am using on my S Type.

Of course I meant a 1969 S Type, they didn't make them in 1959...

I would have thought that, if using an Avon Speedmaster on the front, the best matching rear tyre would be an Avon SM. On my Dominator, I use a 3.25-19 Speedmaster front tyre (thinking this may compensate for the extra weight I have put on since my teens!), and 3.50 SM rear. Although I now seldom ride in excess of 80 m.p.h., I find the bike steers better with slightly higher front tyre pressure than recommended (I use 30 p.s.i.).

Roadriders are light years ahead of the speedmasters, 90/90 19 on the front 100/90 19 on the rear.

Maybe, but were they available in 1969? I suspect not, so they would not be correct for the bike in question.

Previously wrote:

Roadriders are light years ahead of the speedmasters, 90/90 19 on the front 100/90 19 on the rear.

Get real, safety and usability takes priority over originality. What is the point in not taking advantage of 43 years of tyre development. I suppose your still using brake shoes with asbestos?

Not convinced Roadriders are light years ahead of Speedmasters. Talk to the guys at Malksham. The Speedmaster tread may not have changed but the rubber most certainly has. I have tried Roadriders but have found them to be no better or worse than Speedmasters. Believe it or not, Speedmasters have had the benefit of 43 years of development too.

True, different profile though.

I'm sure no Commando was ever supplied as standard with Avon SM tyres on the rear. The ribbed SM front will probably give a stable ride but ribbed tyres are unlikely to perform well IMHO when it comes to using the front brake in anger. That would be worth looking at if you have a front brake that is any better than the original TLS disaster. (early disc brakes were probably no better). If originality is all you are interested in, fit old fashioned tyres and ride in an old fashioned way. If you intend riding in a sporting manner, and lets face it, that is what the Commando is all about, treat yourself to some modern tyres.

In an interview with the man from Avon, he pointed out that although they use the old moulds, it would not be feasible to use the old tyre compound, so the old pattern tyres do have the current rubber compound. So a new Speedmaster is rather better than a NOS one which has been lurking in a shed for 40 years. In the end, tyre choice is a very individual thing. Different tyres for different priorities. TT100 for trackdays, Speedmasters for serious touring and a whole host in between. I still like outcornering modern bikes on my skinny Speedmaster/SM combination. One day I might grow up.

I think thoughts of growing up should be resisted.

I like Roadriders but it is not based on any ultimate performance difference with the more traditional choice. Given the other variables involved, road condition, temperature, wetness etc, it is not possible for the casual rider to be sufficiently discriminating. I believe I feel more secure as I turn in with Roadriders but I haven't used the Speedmaster/SM combination for some years so this is quite unreliable evidence.

Nobody has mentioned tyre pressure but this has to be considered. Extracting a recommended pressure from a tyre manufacturer for a contemporary tyre fitted to a classic bike is just about impossible but original Norton figures will be irrelevant for modern tyres. The advice given by the NOC and other sources varies widely. So suck it and see?

Avon do give recommended pressures albeit with a wide tolerance, I assume within their recommended range the pressure isn't that critical. From memory, for a Commando with Roadriders pressures are something like front 29-32psi and rear 30-34psi, but phone (01225703101) to check for whatever you decide to fit. Don't grow up Gordon, just keep on leaning that Norton!

Previously wrote:

Avon do give recommended pressures albeit with a wide tolerance,

You are right; I was forgetting that this thread is in the Commando section. Avon recommend

Front Tyre

Rear Tyre

I read somewhere that after some spirited riding tyres should have warmed up and accordingly the pressures should have risen by 10%, if not then the pressures are too high and not enough flexing is happening,if more than 10% rise then too soft.I set my wagon tyre pressures by feeling the temperature with my hand after crusing at 60mph . This has worked for the last 20 years.

You don't say where you got your info. Alan but I'm surprised Avon recommending the sizes you quote for an early Commando, especially the rear 18"dia. Caused problems with my bike, much better with 19" dia. front and rear.

You are right, Simon. Norton never fitted an 18" rear wheel to a Commando, although they did fit them to some featherbed models for export to North America. 18" rear wheels on Commandos are a bodge done by some owners for no apparent reason other than maybe they like the look.

Colin.

Previously wrote:

You don't say where you got your info. Alan but I'm surprised Avon recommending the sizes you quote for an early Commando, especially the rear 18"dia. Caused problems with my bike, much better with 19" dia. front and rear.

The Atlas had an 18" rear for all markets, although it was contrary to Norton doctrine. It's not really true to say that 18" wheels on Commandos are a bodge. Many of us tried them out at a time when the only realistic options were the old RoadRunners or TT100s and tyre developments were leaving these types behind. Alternatives simply weren't available in 19" .

You can't really blame us for questioning the original fitments, bearing in mind that Norton's installation of 4.10" tyres on a 1.85" rim was never in accordance with tyre manufacturer's preferred sizes.

Personally, my 850 was never more stable than with a 110/90V18 Michelin M48 in the back. Unfortunately they discontinued them and the replacements (Macadams, I think) were white liners.

I'm now deliberating whether to put new tyres this year onto my WM2 /WM3 19" rims or to continue with the WM3/WM4 18 inchers. To be honest, neither size ever caused an instability problem that I could put down to wheel size but from an aesthetic point of view, neither the 90/90 19 or the 100/90 18 look right under the big 850 front mudguard but I don't have a front hub laced to a WM3 x 19" that would be the correct fitment for a 100/90 tyre.

It does need to be borne in mind, I think that 750s and 850s don't have the same steering geometry.

Personally, in answer to Mike's original question, if I wanted to ride the bike, I'd try 90/90 and 100/90 19" Avon Roadriders on the fastback. Don't worry about them looking a bit narrow. It's part of the period charm and they really don't need more tyre. The 3.00 front does sound small but they specified it up to 1971 so they must have had their reasons. Oddly, it's smaller than my 16H has on the front (the same WM2 rims though).

Simon previously wrote:

You don't say where you got your info. Alan but I'm surprised Avon recommending the sizes you quote for an early Commando, especially the rear 18"dia. Caused problems with my bike, much better with 19" dia. front and rear.

My info is a copy & paste from the page that came up when I entered Norton Commando into the Avon Tyres manufacturer and model search. I didn't read the detail, more interested in Dommies at the moment. Sorry for confusion.

Alan Previously wrote:

Simon previously wrote:

You don't say where you got your info. Alan but I'm surprised Avon recommending the sizes you quote for an early Commando, especially the rear 18"dia. Caused problems with my bike, much better with 19" dia. front and rear.

My info is a copy & paste from the page that came up when I entered Norton Commando into the Avon Tyres manufacturer and model search. I didn't read the detail, more interested in Dommies at the moment. Sorry for confusion.

Try this search on the http://www.avontyres.com/:

My experience and that of a few of the other riders here in Bristol is that Roadriders on a Commando are better thaneither Roadrunners or TT100's.

Otherwise must also admit that the modern SM is immeasurably superior to the old rock hard rubber found on SM's a few decades ago.