Racing Tires for Commando and other Nortons

motorson

motorson

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I talked to the Continental tire guy at the Carolina Motorsports Park during the AHRMA races last month. He only had 18" racing tires suitable for Nortons and of course recommended that rims be changed to fit his tires. A bit of an internet search of Bridgestone and Dunlop also came up with no good options in the 19" size for racing tires. Avon makes an AM26 Roadrider in a soft compound 100/90 19 size and the 18" size in that line is only 90/90. What are AHRMA racers using on bikes that typically came with 19" tires?
 
Those are pretty narrow for a commando. The AM26 I mentioned is 2cm wider and available in soft and medium compound. A lot of Commandos have been running the rear wide tire on both ends for years so that might be a possibility.
I'm wondering what others are actually running at the track.
 
Hi Motorson
Got to say I don't know anyone running 19" tyres on a Commando in the UK.
I will ask around as its BHR at Mallory Park next weekend & their bikes are more original.
 
A few months ago I found reference in the web to an 18 inch Dunlop K81 in race compound. But I am stuck with using 20 year old Bridgestone Battlax. They do not seem to have gone hard. I have been riding so long that I am not very tyre dependent. I don't fly into corners and chuck the bike into full lean. When I was a kid I raced on T1 compound triangulars. There might be a profit in somebody financing production of 18 inch race tyres.
 

Dunlop Classic & Vintage Tyres​

The K 81's still around , if you consider them ' racing ' tyres !

Ancient Conti's were designed to swap ends rather than loose the front .What you did when you were backward at 60 , was another question .
( Intentionally designed for lower coefficent of friction , rear . Has to be experianced to be believed , Got the old tyre tech artical on them . )

The ' R ' series had Race carcase ( cords ) with soft sides & firmish middle , was only 42 years ago , but if there is still a ' R ' or equivilant case ,
you could walk it into a tight turn & catch it on the power . the TRIGONIC bit meant setting it up , over . Upright / transition was less grip .
Narrow bottom was less drag , so they were 2 or 3 mph quicker top end , with the lesser rolling resistance . So If You ' RUN THE BENDS ' on
the throttle , and up n over , PRIMARILLY BANKING , theyre quick . If you cant run a constant lean well over at your track , throttled up
theyre hardly worth it .

If your reliving the glory days , however , theyre the Real deal .
 
The ad for the K81s mentioned one type which was race compound. My mate bought a couple of 19 inch Avons for his Manx. I don't know who sells them in Australia, I need to ask him.
 
Matt Spencer said:

Dunlop Classic & Vintage Tyres​

The K 81's still around , if you consider them ' racing ' tyres !

Ancient Conti's were designed to swap ends rather than loose the front .What you did when you were backward at 60 , was another question .
( Intentionally designed for lower coefficent of friction , rear . Has to be experianced to be believed , Got the old tyre tech artical on them . )

The ' R ' series had Race carcase ( cords ) with soft sides & firmish middle , was only 42 years ago , but if there is still a ' R ' or equivilant case ,
you could walk it into a tight turn & catch it on the power . the TRIGONIC bit meant setting it up , over . Upright / transition was less grip .
Narrow bottom was less drag , so they were 2 or 3 mph quicker top end , with the lesser rolling resistance . So If You ' RUN THE BENDS ' on
the throttle , and up n over , PRIMARILLY BANKING , theyre quick . If you cant run a constant lean well over at your track , throttled up
theyre hardly worth it .

If your reliving the glory days , however , theyre the Real deal .
Click to expand...
Triangulars were used on early Manx Nortons, How far can you lean a Manx which does not have an after-market frame with the changed geometry ? Most of the later tyres were designed to be used on two-strokes. The first gumball tyres we saw in Australia were the Goodyears on the Henderson Matchless. The big difference between 1961 and 1971 was the angle of lean. A Manx with 19 inch wheels can be as quick as a Manx with 18 inch wheels, but the lean is different because of the steering geometry which is changed to get the bike with 18 inch wheels to handle. The point is, nothing is achieved bey leaning the bike at an extreme angle - If the bike naturally stays more upright, you can put more power on the ground
 
The 90/90 x 19 and 100/90 Avon AM6 pairing is particularly used for Manx Nortons and G50s where class structures require 19" rims. They are a good pairing and very successful in the application.

They are being made, but that doesn't guarantee they are being imported to the US, you might have to buy direct from the UK.

I have a pair on my Suzuki GT500 race bike which has a 19" front rim (standard) and a 19" rear rim, which is non standard, but the 19" rim was used in period to gain more ground clearance compared to the 18".

These are the only real option in these sizes, but, they are a good one. And I think it will work on your Commando, certainly it would be cheaper to try them before building new wheels.

I have no idea of your engine build which may well be delivering less horsepower than the best Manxes (60+rwhp) and may not be that much heavier! (Depending on what you dumped when building it as a race bike.)

Standard Commando 19" rims will be WM2, and really a narrow tyre will be nearer recommended fit for that rim size.

Remember, early Commandos left the factory with a 3.60" inch front tyre and production Commando's were raced on 3.60 or 4.10 front and 4.10 rear TT100s. Regardless of the small change in size you will still have more grip than they gave if you fit a modern compound race tyre!

I run a 90/90 front on all of my bikes including my Rickman Commando. I prefer the size to wider tyres I have tried.

But, on my Rickman and my SR500 engined single I use 18" Heidenau tyres and like them a lot. 90/90 front on a WM3 rim, and 130/70 rear, however on a 3" rim! You may have some issues with chain run, I have an offset gearbox sprocket and spaced the wheel to suit.... What I would really like to try is a 120/80 or 120/90 rear, but.....no one is making them in race compounds.

Most of the Nortons raced in France are Seeley framed and use 18" rims with either Avon 90/90 AM26 Front with 110/80 AM23 Rear, or Continental 100/90 front with 110/80 rear.
 
And.....I have absolutely no idea what this means:

.....you could walk it into a tight turn & catch it on the power.....
 
SteveA said:
The 90/90 x 19 and 100/90 Avon AM6 pairing is particularly used for Manx Nortons and G50s where class structures require 19" rims. They are a good pairing and very successful in the application.

They are being made, but that doesn't guarantee they are being imported to the US, you might have to buy direct from the UK.

I have a pair on my Suzuki GT500 race bike which has a 19" front rim (standard) and a 19" rear rim, which is non standard, but the 19" rim was used in period to gain more ground clearance compared to the 18".

These are the only real option in these sizes, but, they are a good one. And I think it will work on your Commando, certainly it would be cheaper to try them before building new wheels.

I have no idea of your engine build which may well be delivering less horsepower than the best Manxes (60+rwhp) and may not be that much heavier! (Depending on what you dumped when building it as a race bike.)

Standard Commando 19" rims will be WM2, and really a narrow tyre will be nearer recommended fit for that rim size.

Remember, early Commandos left the factory with a 3.60" inch front tyre and production Commando's were raced on 3.60 or 4.10 front and 4.10 rear TT100s. Regardless of the small change in size you will still have more grip than they gave if you fit a modern compound race tyre!

I run a 90/90 front on all of my bikes including my Rickman Commando. I prefer the size to wider tyres I have tried.

But, on my Rickman and my SR500 engined single I use 18" Heidenau tyres and like them a lot. 90/90 front on a WM3 rim, and 130/70 rear, however on a 3" rim! You may have some issues with chain run, I have an offset gearbox sprocket and spaced the wheel to suit.... What I would really like to try is a 120/80 or 120/90 rear, but.....no one is making them in race compounds.

Most of the Nortons raced in France are Seeley framed and use 18" rims with either Avon 90/90 AM26 Front with 110/80 AM23 Rear, or Continental 100/90 front with 110/80 rear.
Click to expand...
,

' Most of the Nortons raced in France are Seeley framed and use 18" rims with either Avon 90/90 AM26 Front with 110/80 AM23 Rear, or Continental 100/90 front with 110/80 rear.'

The first of those is pretty much what I use on my Seeley 850 , and I have never raced in Europe. It is pretty much what was used on two-strokes in the late 69s, early 70s. That is the era in which the Gus Kuhn Seeleys were raced. That combination of tyres was the best at the time. If you have bigger, or smaller getting them warm quickly might be a problem, and they would probably change the handling for the worst. Bridgestone Battlax tyres are the best I have ever used, But I don't need much because I was brought up racing on rubbish - I have a very gentle touch. I don't even blink when I am riding. fast. My brain is always glued to the rear tyre contact patch.
 
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When I built my Seeley, in 1978 I had raced from about 1969 to 1978. So I knew what it should be like. I think a lot of guys these days do not know, because they were not alive back then. Their knowledge is often in relation to what is used on modern bikes. Modern bikes bear no resemblance to what was raced in 1970. Even a 1980s bike is substantially different, but not necessarily faster. The bikes I race against in Period4 Historic are mainly over-bored CB750 Hondas. They are up to 1100cc capacity and run on methanol. They are the equivalent of a Z900 Kawasaki on methanol. But there was always a problem with late 70s Japanese superbikes - not many of them handled. The XR69 Suzuki which Crosby rode was probably the best of the 70s superbikes. It was a GS1000 with race cams and a close ratio 6 speed gearbox and a trick frame. A Katana engine does not quite cut it. That is what most guys use in the replicas.
 
SteveA said:
These are their current classic race tyres, 18" only:

www.conti-bike.co.uk

Motorcycle tires

Continental relentlessly researched, tested and invented motorcycle tires, covering hundreds of thousands of kilometers and applying for numerous patents.
www.conti-bike.co.uk www.conti-bike.co.uk
Click to expand...
SteveA said:
And.....I have absolutely no idea what this means:

.....you could walk it into a tight turn & catch it on the power.....
Click to expand...
I know what it means and I don't do it. My bike spins the back wheel free when I try to do silly things with it's power.
 
AHRMA guys run Avon Roadriders, although mostly 18"ers. These are considered the best tube-type tires for roadracing.
 

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