Tyre pressure

Previously Dave Young wrote:

Could anyone please tell me the correct tyre pressure for my Norton model 50 1957 350? I've only had it for two weeks and can't find the info.

cheers Dave

Hi Dave,

Best to try out several different pressures and find what is optimum for you and your roads.

I run Dunlop K81's (TT 100) on my 1952 plunger ES-2 and 1965 650SS. The ES-2 I prefer 24psi front and 26psi rear and on the 650SS 28psi in both. (But I am 96kg)

regards, Ian

Book pressures are 25psi front, 22 psi rear which I find perfectly satisfactory. Some people advocate higher pressures. In my experience, higher pressures give a harsher ride and make the bike skittery in the wet. The choice is yours.

Hi Dave

My understanding is that the rubber used in tyres now is different to what it was in the 50's so tyre pressures suggested then may not work now. It's a bit of trial and error to decide what you like.

I weight about 100kg and have 27-28 in the front and about 30 in the back of both my Inter and my 350 Royal Enfield. Both are rigid rear end and ride very nicely.

Quite right about the rubber being much improved these days - but if you are using for instance Avon SM and Speedmaster tyres, as I do, the carcass construction hasn't changed so the old pressures still apply. However, if you choose newer type tyres, check with the manufacturer for pressures.

We had an Avon tech man come & give us a talk at a branch meet a while back & he suggested going up about 2psi on manufacturers recomended pressures for SM's & Speedmaster's & 4-6psi more if using new style Roadrunners or Roadriders. His reasons were that the new compounds & bracings used are a little more flexible & therefore need a bit more pressure to keep their shape & to stop them overheating. I've followed his advice & it works for me on Roadrunners (Commando) & SM/Speedmasters (Dommie).

Regards, Tim

+1 for 2psi as Tim suggests.

Deathmasters have become much lighter over the years and now weigh only a third of their original mass, scale of economies and the buying in of modern materials mean it makes sense for the manufacturers to build them of the same stuff as their modern counterparts.

I have used the following method to establish tyre pressures for unusual situations, such as a heavily loaded bike setting off on a long tour.

[1] On a cool but not wet day set off on cold tyres and drive for 15 mins, stop and check tyre temperature. Tyres should be warm to the touch but not hot.

[2] Cold tyre is not warming up enough- lower pressure by 3 psi, try again.

[3] Too hot a tyre is running "flat", increase pressure by 3 psi. try again.

Pressures:

[4] As a guide, the difference in pressure between setting off from cold and up to working temperature should be about 3 psi.

[5] Should you check pressures and find an increase on the starting pressure of more than the desired 3 psi [as in #3 above]the tyre will be running too hot and needs more pressure to start with.

[6] Conversely if you find that the pressure has not risen 3psi since the beginning of the run, lower by [yes you guessed it] 3 psi

As an aside, has anyone else noticed that some modern inner tubes, even those from major manufacturers, seem to need checking more often nowadays?

I can't be alone in this, my ES2 and a tubed tyred BMW of my aquaintence both require checking on every instance of being used. I think the air holding abilities of inner tubes available now is not what it used to be!

Rob.

I forgot to add that I run Heidenau K34 tyres at the originally specified sizes, 3.25 front and back. Try Googling them.

They run well and I think look the part on a '49 machine.

I run them at 24F 29R.

I got into Heidenau after discovering that all the German/Dutch Etc. "adventure" types doing long distances on big trailies were using them. Have to say that I've used them in those same conditions they are a pretty good choice.

Rob.