Author Topic: A50 wheel/tyre sizes  (Read 1171 times)

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Splodger

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A50 wheel/tyre sizes
« on: 23 February, 2019, 12:17:12 »
Just got hold of a 1970 A50 Royal Star (reminds me of the Spitfire I had in 1969!) and am puzzled by wheel size/tyre.
Front and rear rims are Borrani WM3 18. Both tyres are 3.25".
Are 18" wheels the norm? If so, what tyre size on the front/rear would be best.
The bike has a couple of Czech tyres at present but I'm likely to ditch these for better-known items - unless someone knows differently?

Mike Farmer

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Re: A50 wheel/tyre sizes
« Reply #1 on: 23 February, 2019, 13:33:28 »
 :)

I have 3.25 x 19 on the front and 4.00 x 18 on the rear. I think that's what the book says. Mine is Feb 1963.

Mike 8) 8) 8)

ChrisG

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Re: A50 wheel/tyre sizes
« Reply #2 on: 23 February, 2019, 13:46:28 »
Mine is a 1970 like yours and has a WM2 -19" Front and an WM3 -18" rear. They are correct according to the parts list.
Chris

Splodger

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Re: A50 wheel/tyre sizes
« Reply #3 on: 23 February, 2019, 13:58:55 »
Thanks for the feedback. I'd prefer a 19" front and I think that I'll have to change the rear to a wheel which will accommodate a 4" tyre rather than the thin beast currently fitted. So good start to my reacquaintance with A50/A65 - great bikes. Early days yet to get this old girl into a presentable state.

bikerbob

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Re: A50 wheel/tyre sizes
« Reply #4 on: 23 February, 2019, 14:42:49 »
According to Roy Bacon's book on the A50/A65 twins 1962 /1972 the A50R from 1966 to 1970 had a 3.25X19 on the front and a 3.50X19 on the rear with the exception of the 1967 which had a 4.00X18 on the rear.

Splodger

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Re: A50 wheel/tyre sizes
« Reply #5 on: 23 February, 2019, 14:52:38 »
Thanks Bikerbob,
Most of my old BSAs had 19s front and back, I'll head down that road.

ChrisG

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Re: A50 wheel/tyre sizes
« Reply #6 on: 25 February, 2019, 16:39:46 »
Well unfortunately Roy Bacon was incorrect in that statement as, according to the parts lists the A50 Royal Star did have 19" rear wheel up to 1966 model year but after that they had 18" as standard.
Its up to you, but I think that if the item was fitted when new, it was for a reason. In the case of wheel & tyre sizes, I have always assumed they handled better with the ones they fitted.

Splodger

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Re: A50 wheel/tyre sizes
« Reply #7 on: 05 March, 2019, 11:32:22 »
Thanks for all of the replies thus far.
I'm stepping back from 19" front and rear. One big persuader is that both existing Borranis are 18" WM3 rims and I'm thinking that tyre dia is a more significant issue than wheel size.
I can get Avons front 90/90 at overall dia of 619mm and 110/80 rear at 640mm dia. This isn't greatly different from the tyre dias currently on board (they're cheapies from Czech Rep which I will change). Now, alternatively, I can get a 4.00-18 rear with an overall dia 671mm!
With regard to handling (key issue) which is the preferable rear tyre to get?
Does anyone have a persuasive observation?