[Arizoni]

A few years ago I got a copy of the book, "GREAT BRITISH MOTORCYCLES of the 1950s & 1960s" by Bob Currie.

It is basically a bunch of reprints of the motorcycle reviews published in THE MOTOR CYCLE .

In the information in each review it lists the tire sizes for each motorcycle and I thought it might be interesting to make a list of what it shows.  The list is in the same order as the articles in the book and I added the engine size (rounded off)  for reference.  f = front,  r = rear

It starts off with the Vincent Black Shadow, one of the largest and fastest of the British motorcycles.
Using modern logic, that beast should have massive tires on it but it doesn't.  Curious.

1949 VINCENT BLACK SHADOW--1000cc, 3.00 X 20 f, 3.50 X 19 r
1950 ROYAL ENFIELD BULLET--350cc, 3.25 X 19 f, r
1950 ROYAL ENFIELD TWIN--500cc, 3.25 x 19 f, r
1951 ARIEL RED HUNTER--500cc, 3.00 X 20 f, 3.25 X 19 r
1952 BSA STAR TWIN--500cc, 3.25 X 19 f, 3.50 X 19 r
1952 TRIUMPH TIGER 100--500cc, 3.25 X 19 f, 3.50 X 19 r
1956 BSA B31--350cc, 3.25 X 19 f, r
1953 ARIEL SQUARE FOUR--1000cc, 3.25 X 19 f, 4.00 X 18 r
1954 VELOCETTE MSS--500cc, 3.25 X 19 f, r
1956 TRIUMPH TIGER 110--650cc, 3.25 X 19 f, 3.50 X 19 r
1957 TRIUMPH TIGER CUB--200cc, 3.25 X 16 f, r
1958 NORTON MODEL 99--600cc, 3.00 X 19 f, 3.50 X 19 r
1961 MATCHLESS G12--650cc, 3.25 X 19 f, 3.50 X 19 r
1961 ROYAL ENFIELD CONSTELLATION--700cc, 3.25 X 19 f, 3.50 X 19 r
1962 NORTON DOMINATOR 650SS--650cc, 3.00 X 19 f, 3.50 X 19 r
1962 AJS MODEL 18--500cc, 3.25 X 19 f, 3.50 X 19 r
1962 BSA ROCKET GOLD STAR--650cc, 3.25 X 19 f, 3.50 X 19 r
1964 TRIUMPH BONNEVILLE--650cc, 3.25 X 19 f, 3.50 X 18 r
1966 ROYAL ENFIELD CONTINENTAL GT--250cc, 3.00 X 18 f, 3.25 X 17 r
1967 BSA B44 VICTOR--441cc, 3.25 X 18 f, 3.50 X 18 r

Based on these sizes, it looks like my 2011 ROYAL ENFIELD DELUXE is right where it should be when it comes to its tires.

[hpwaco]

Must be for UK spec bikes.   Having removed it several times, the rear tire on my then new '62 Triumph T120 Bonneville definitely was a 400-18.   I believe that my '63 Triumph T100 S/C rear tire was also a 400-18 (universal).   Never did like the skinny 350-19 rear on my '02 Bullet ES - among other things - that's why I got rid of it and kept my '01 Bonneville for another 15 years!

[Stanley]

Old guy here....Back in 1971 I had $900 for a bike, and had the choice of a near-new CB750 or a leaky Vincent Black Shadow. The Vincent looked spindly and feeble on those narrow rims and parts were scarce, so I went with the Honda and wore out a number of 4 inch K81s, the fattest tires available. My friend showed up with one of the first Z1s, shod with the same 4 x 18 rubber despite an extra 20hp. We were used to "stepping out" in the turns, with the swingarms oscillating in sloppy bushings.
Modern tires are the best riding improvement I've seen next to disk brakes, but I sure miss paying $22 for a tire!

[Adrian II]

ISTRC the specifications for British bikes exported to the USA (at least for some makes) could vary depending on whether they were intended for the East Coast or the West Coast, which would include rear wheel size.

A.

[Richard230]

I just replaced both of my 7-year old B5's Avon Slipmaster II tires today with the recommended Dunlop K70 rubber. These are the same tires that came stock on my 1971 Triumph Bonneville. They were really crappy tires back then. Fortunately the new version seems better. 

[Arizoni]

Stanley:

So, how many times have you kicked yourself in the arse for not buying the Vincent?

Had you kept them your 1971 CB750 might be worth $8000 today if it was in tip top condition.
The Vincent could sell for $40,000 if it is in poor shape.  In top condition it could easily top $120,000 in today's market.

[Stanley]

I have no padding left from kicking me arse. I once watched a skiploader at a MC junkyard fill a dumpster with BSAs, a few Sunbeams and preunit Triumphs. I rode Brit and Euro bikes back when they were almost free for the taking. Everyone wanted a Japanese machine.

[Scotty Brown]

Stanley is still with us because of the Honda--With the terrible brakes on the Vincent he might have been the late Stanley.  Oh yes I do remember the built to go, not stop language. STOP takes it in Spades every time.

[Stanley]

I tend to agree. I spent some time on an Ariel 4 and told the owner it seemed the brake linings made less friction than the wheel bearings.
He lost his life on that bike a month later.