Tyre pressures

[RDfella]

And remember that modern tyres need to be inflated harder than period tyres
Put 24 PSI in a modern tyre and you are just begging for the tyr to walk around the rim & rip the valve out  of the tube .

Not sure I can agree there - assuming one is using a similar type of tyre to that originally fitted.
My Honda runs 46psi in the rear (tubeless) but I presume we're talking classics here so, if by 'modern' we're talking a different design of tyre, maybe - but, like using modern oils in our engines, I don't advise using something potentially incompatible with a classic. Especially tyres - could that, for example, invalidate insurance?
I like Avon Speedmaster and Dunlop K70. The ones I buy nowadays are softer than those I take off, but that's because they're 20+ years younger, not because of different construction. 
I run 20psi in all my road-going classics (18psi in the rear of my rigid) and never had a tyre slip despite the rigid pushing out around 50 / 55 bhp and one of my GF's nearer 70. No tyre clamps either. When pressures were being discussed a while back, I tried high 20's in one of my GF's - couldn't wait to get back and lower the pressures. Handling and ride quality was unacceptable.

[BagONails]

I'm pretty sure latter day K70's such as fitted on my GF will stand 10psi higher than the original recommended pressures per Haynes etc. They are old style tread with modern compounds and construction.  We're getting onto a different topic here with tyre pressures but I run 30psi rear and 27psi front and check them every time I go out.

I've found anything less than 24 in the front and the steering is nowhere near as sharp.

Low pressures are potentially dangerous on high powered bikes, its really all that stops the wheel spinning inside the tyre. Less of an issue on GF's of course!

More of an issue here in the summer granted (41 degs here today) but under inflated tyres run much hotter due to side wall flex and your chances of a blow out increase considerably as result, regardless of how many nuts you have or how big they are!

[BSA_54A10]

And remember that modern tyres need to be inflated harder than period tyres
Put 24 PSI in a modern tyre and you are just begging for the tyr to walk around the rim & rip the valve out  of the tube .

Not sure I can agree there - assuming one is using a similar type of tyre to that originally fitted.
My Honda runs 46psi in the rear (tubeless) but I presume we're talking classics here so, if by 'modern' we're talking a different design of tyre, maybe - but, like using modern oils in our engines, I don't advise using something potentially incompatible with a classic. Especially tyres - could that, for example, invalidate insurance?
I like Avon Speedmaster and Dunlop K70. The ones I buy nowadays are softer than those I take off, but that's because they're 20+ years younger, not because of different construction. 
I run 20psi in all my road-going classics (18psi in the rear of my rigid) and never had a tyre slip despite the rigid pushing out around 50 / 55 bhp and one of my GF's nearer 70. No tyre clamps either. When pressures were being discussed a while back, I tried high 20's in one of my GF's - couldn't wait to get back and lower the pressures. Handling and ride quality was unacceptable.

Well perhaps I should have said it differently
USE THE MAKERS CURRENT PRESSURE RECOMMENDATIONS not those in the riders handbook.
I have not fitted a Dunlop for quite some time
However when I ran them at the recommended pressure in my riders handbook, torn valves were a regular occurance
Once I switched to the tyre makes recommendations, torn valves ended .
The caveat here is I did drop the pressure a bit for the reason of comfort on the rigids but from memory I run 28 & 30 in the M20 as comparred to BSA recommended 20 & 22
The makers recommended 34 but that made the girders work way too hard  and the back too skittish.
Thyre compounds & tread patterns have changed a massive amount since our bikes were new .

[Black Sheep]

Not forgetting that with primitive suspension (or the complete lack of it) the tyres have to flex a bit or roadholding and comfort are compromised. I've never had a tyre slip on a rim even using book pressures. Nowadays I ride on book pressures + 2 psi.

[Worty]

Bit like a oil thread is this one.

On the Beeza, I run 30 in the Cheng Shin front and 34 in the AM26 rear, works as well as I could hope for, especially on peg-scraping bends.  On the Kwaka, I run the same with Battlax front and rear.  Did try book pressures to begin with before realising they were for 'girder' tyres which could probably run with no air at all.

[BSA_54A10]

Modern tyres are nat made for anchient rims
By & large most are now designed for cast rims.

Now perhaps it is because I tend to ride a touch on the quick side and usea lot of engine brakings
But then rear will happily rip out a valve
Never a poblem from the front wheel .

I went to Trouper Lou one time to get a new tyre fitted while I walked up to RGS 200 meters to pick up a parts order
Naly killed myself when I left, bike danced all over the road

they had fitted it to the correct ( for the tyre ) pressure of 34 psi