Disc Brakes on rear?? any ideas

[Iain Hall]

On my Clubbie I have found that the tyre presure that I run is crucial to the ease with which the wheels will lock-up. Given the fact that the physics is the same for a Morris Minor I can't help wondering what sort of tyre pressures people are running in their cars, especially when they have gone to modern radials and or wider wheels. My clubbie runs at just 18 pounds front and rear much more than this and I get bugger all traction and easy lock up, it only weighs 630 kg where as a Morris weighs what, a bit over 700kg? (according to what I've read)

Has anyone done some serious experimenting with tyre pressure to find the optimum for modern tyres to get a better trade off between traction and economy?

[MartinB]

What is your Clubbie?

[Iain Hall]

an N16 Nissan engine:

[Innovator]

Has anyone done some serious experimenting with tyre pressure to find the optimum for modern tyres to get a better trade off between traction and economy?

I use tyre temps to set my pressures. If they are too hard then the centre will run hotter than the inside and outerside edges, too soft and the inside and outer edges will be hotter.

[bmcecosse]

If I run any less than 30 psi - the handling is like driving a jelly........ But I agree that on a wet road it can be all too easy to lock wheels - but then the tyres are not exactly high tech.... I do drop the pressure to ~ 24 when I take the car for it's annual test - so they will grip the test rollers rather better. 18psi sounds very low - do the tyres not get very hot - no side wall cracking problems ??

[Iain Hall]

bmcecosse

My Clubbie weighs just 630 kg so 18 PSI works out just about right in terms of getting the right balance between reducing rolling resistance and maintaining traction, in fact the car is so light that when I have a flat I can still drive the car. I am getting two new tyres on the back tomorrow as i am finally replacing the the rubber that was on the wheels when I bought then second-hand off eBay five years ago. I expect that the tyre fitters will be as surprised as you are when I tell them that I want them set at 18psi.

[rayofleamington]

I use tyre temps to set my pressures. If they are too hard then the centre will run hotter than the inside and outerside edges, too soft and the inside and outer edges will be hotter.

That sounds very sensible for getting optimum grip and even wear...
How long do you drive before checking temps and does it need to be mainly straight road?

I've seen a lot of Minor tyres worn low in the centre due to excess pressure - probably a growing trend as more people want the extra half an mpg.. Certainly the 'feel' of the Minor is more similar to a modern car when the tyre pressures are high.

[Innovator]

I use tyre temps to set my pressures. If they are too hard then the centre will run hotter than the inside and outerside edges, too soft and the inside and outer edges will be hotter.

That sounds very sensible for getting optimum grip and even wear...
How long do you drive before checking temps and does it need to be mainly straight road?

I can not remember the exact distance (10 miles?? ) but is was the A1 which is straight enough then I could pull straight off into a layby and jump out and measure the temps.