Tyre choice, advice sought.

Information relating to the Matchless G15 or AJS Model 33 750cc twin. This also includes the G15 Mk II and the G15/45
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schwantzz
Posts: 23
Joined: Fri Aug 12, 2011 12:14 am
Location: NORTHANTS UK

Tyre choice, advice sought.

Post by schwantzz »

After much deliberation I decided that I wanted to kit my G15cs out with some trail tyres to suit the style and image of the desert racer. Having actually chosen and ordered a suitable pair I then discovered that my rear wheel is actually 19" not the 18" I thought it was - doh!

So with no 19" rear available in a trail type i've had to have a rethink. Having the 19" rear really narrows the choices down.
I'm thinking of ordering some Dunlop K81 TT100's tomorrow. Well I am going to the TT on the bike!

Will a 19 x 3.60 front and 19 x 4.10 be ok size wise? very slightly wider than std.
I think the std sizes are 3.50 front, 4.00 rear but please correct me if I'm wrong.

Or perhaps suggest better alternatives. I can't really explain why but I don't like the Avon ribbed front so am trying to avoid that.
schwantzz
Posts: 23
Joined: Fri Aug 12, 2011 12:14 am
Location: NORTHANTS UK

Tyre choice, advice sought.

Post by schwantzz »

After a bit of Google searching I cam across this article on the Norton website which has a nice explaination of tyre options and size comparisons etc... It is written for the Commando but I'm sure some of the advice will be valid for the G15CS.
Of particualr interest to me was were these bits -
"So Norton decided to equip the new Commando with a version of Avon's 3.50-19 roadracing tire, the "GP". This was a cheap, second rate racing tire- the Dunlop KR series "Triangulars" were essential for serious racing- but the GP was miles ahead of any street legal tyres available then. At the same time or soon after, Avon decided to do something about the fact that a tire designated "3.50" was actually a little over four inches wide. Till then, tire sizes had always advanced in quarter inch steps- 3.00, 3.25, 3.50, etc. The new code used selected intermediate numbers, so the 3.50-19 racing GP became the 4.10H19 original equipment rear tire for the Commando. The 4.10 told you it was equivalent to a 3.50, but "low profile", or wider (4.10") than it was tall."

and

FRONT TYRES
"The 3.60 Dunlop K81 or Avon Roadrunner Universal, which replaces both 3.00 and 3.25, is an excellent choice"

REAR TYRES
"The Dunlop K81 incorporated in a street tire some of what Dunlop had learned on the track with the KR series Triangular racing tyres. It was the second tire to adopt the 4.10H19 designation, and was a world better in every way than the Avon GP. It bears two extra names, "Roadmaster", and more meaningfully, "TT100", because they were used on Malcolm Uphill's Triumph T120 Bonneville to attain the first 100mph lap of the Manx TT course by a production bike (1969 Production TT). First made in Britain of course, by the late 70s and early 80s, they were variously manufactured in Ireland, France, and the USA. Since Sumitomo, Dunlop's former Japanese subsidiary, took over Dunlop worldwide, K81s are made in Japan."

SUGGESTED TYRES
All around riding:
Front: Dunlop 3.60H19 K81 or Avon 90/90H19 Roadrunner Universal, if you can find either one.
Rear: Dunlop 4.10H19 K81 or Avon 100/90H19 Roadrunner Universal
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Rob Harknett
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Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Tyre choice, advice sought.

Post by Rob Harknett »

I would had thought there is a trails tyre to suit the rear wheel. Were you looking for 400x 19? this was balanced out with 300 x 21 front. So the bike was horrizontal.
2 x 4.00" + 19" = 28"
2 x 3.00" + 21" = 28"
You will notice from Steves suggested tyre sizes, the bike will be one inch higher at the back. So it does not seem to matter if the tyre sizes do not allow the bike to be horizontal. In fact I often fit 3.25 front and 3.50 rear tyres on my bikes.
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