I've just had a chat with Vintage Tyres in Beaulieu and they seem to think their own Ensign tyre in 3.50 x 19 front and back should be a good fit for looks and performance. Avon are all old stock until the new factory starts producing later this year.

Hi Eddie, I took the jet block out and found the hole you  described. The smallest of the three. I took a very fine copper wire and pushed it in the hole. This didn't go all the way to the centre but as far as another corridor in the block. Is this correct or does the small hole extend through the corridor to the centre? Thanks. By the way, the jet block is so slack it just falls out  of the carburettor now. Maybe it's not getting pushed up to align with the carburettor intake holes. What thickness fibre washer should it be under the jet block?

Paul,
        Further to my previous message - attached is a scan of the centre pages of the T35 Mk1 handbook (showing the dimensions and fits).

Regards, 
             Eddie.

On rechecking, the present rear actually is a Mitas 4.00 x 19 and clears the shaft without probs.
Perhaps I should just fit new Mitas front and back?
Apart from the general advice is to replace tyres after 10 years, I'm looking for a comfortable, safe ride and tyres get really hard when they get to be 40 years old. My postwar Doug needed an angle grinder to cut off the ancient tyre on it, and it was so solid it looked fully inflated even when it had no pressure in it.

Paul,
        The only postwar model that Douglas published a list of limits and fits for was the T35 Mk1. In that handbook, they suggested the crankshaft endfloat should be between .005" and .014". This figure was obtained by shimming between the oil retaining plate (large hardened washer) and the shoulder on the front mainshaft. These early models had a one-piece front main bearing bush whereas your Mk4 should have a two-piece bush.

  Hope this helps,
                          Eddie.

Sweetnigel,

I use on my pre - 1940 Douglas bikes (not Endeavour) most Mitas tires (czech made), because they have a nice old-fashioned, near to old Dunlop, surface. quality is good and price is okay.

May be a 4.00-19 rear is a bit fat?
Is there enough clearance to the shaft drive?

Michael

Thanks for that Ron.
Sadly, documentation for the Endeavour is almost non-existent but the sales brochure quotes 
"26 x 3.25 Dunlop wired" for the tyres.
I wonder what sort of Dunlop that would have been?
The present tyres are not the same brand, nor can I can find them now - the rear is around 40 years old and the front even older!
My instinct is to go for 3.50 x 19 Avon Speedmaster front and matching Avon SM rear 4.00 x 19.

As has been suggested here before, the factory likely didn't even own a torque wrench when 
these bikes were built, so any suggested torque figures should be viewed in this light.
Doing things by feel was how they did it then - folks with a gorilla grip need not apply. !!

Sticking to a table of possible torques for common bolt sizes gives approx
8 ft/lbs for 1/4" bolts,  15 ft/lbs for 5/16 bolts and 20 ft/lbs for 3/8" bolts.
If all hi-tensile steels are involved, these can be increased a little.
If this feels too much, don't persist !
Larger fittings - sprockets and crankshafts for example - can require a good heave.
And bolts/studs into alloy should be treated with some caution, & Loctite is good here. ?

Someone may chime in with some tried, true and tested numbers here. But again, treat with slight caution ?.
Hopethishelps.

As you can imagine, a blanket one-tyre type recommendation suits all is highly unlikely.

What brand and type are your present 3.50 x 19 front and 4.00 x 19 rear ?
Fortunately, tyres for classics haven't changed a whole lot - if they have served you well, 
you should be able to find something very similar today.



Tyres in the 1930s were likely to have been possibly 3.25 x 19 both front and rear.
(what does the handbook say ?).
With fairly stiff sidewalls, so low-ish pressures would suit.
Modern tyres tend to have softer sidewalls, so always read the pressures suggested,
likely imprinted in the sidewalls - 28 to 30 psi -ish is common.
Hopethishelps.

I'm looking to replace the tyres on my 1936 Endeavour. Presently fitted are 3.50 x 19 front, and 4.00 x 19 rear.
Firstly, what make and sizes would have been fitted in the 1930s?
More importantly, what make, model and sizes should I fit in 2025?
I believe the rims to be the originals.