over inflating is dangerous for one it will increase the risk of a blown tyre and the tyre will not grip properly on the road very hazardous in the wet it will also increase braking
at 32 front 33 rear thats with 3 adults each weighing 12 stone since its mainly only me i sit at 30 front 31 rear which gives me the best balance of extra grip in dry and wet
I have found that i get more grip from the higher pressures i run, better braking, shorter braking etc
One of the things i mentioned in one of my previous posts was the low pressures are ok for popping down to the shops, but not for high speed or heavily laden
This is a statement from a tyre manufacturer -
"Heavy loads or towing puts an extra strain on your tyres. So if your vehicle is fully loaded with passengers and luggage, the general rule is to add 28kpa (4PSI or 4lbs)
At high speed, (defined as driving at 120km/h for over one hour), your tyres will wear out twice as fast as when you drive at 70-80 km/h. If your tyres are under-inflated by twenty per cent tyre life can be reduced by thirty per cent. The rule here is to add 28Kpa (4PSI) from your Minimum Compliance Plate Pressure.
Believe it or not, checking your tyre pressure can have a big impact on our environment. An under-inflated tyre creates more rolling resistance and therefore more fuel consumption. By keeping your tyres inflated to their proper levels, you can help maximise your car's fuel economy and minimise its impact on our environment."
^^a quote from Bridgestone^^
So if the "Minimum Compliance Plate Pressure" is at 32 front 33 rear, thats at 50mph, at 70mph it should be +4PSI = 36 front 37 rear - thats Bridgestones' recommendation, (Focus - for high speed)
So an extra 4PSI over the plate if you don't drive like your granny
But of course, if you know better than Bridgestone.......
- i have also seen Ford recommend 40PSI for the rears when heavily laden, on another site, 41PSI is the recommended pressure for the fronts (thats on a Mondeo though) so in these cases, 40 and 41 PSI are not "over inflated"
It took me a long time and a lot of experimentation to find the "ideal" 39-front 41 rear (Mondeo) for me, im thinking of dropping these pressures a couple of PSI due to the warmer weather
At lower pressures you won't get any heat in the tyres so grip will be reduced,
and rolling resistance will increase (According to me, and Bridgestone, anyway )