tyre pressure

wolfehouse

i went on a long roadtrip and increased the tyre pressure as instructed in my manual for a fully loaded car.

should i now try to empty the tyres and get them back to the recommended small load pressure? I guess i just want to understand the reasoning behind the different pressures (one for the brainiacs)

joshm_2

I'll take a stab at this one - I assume it's related to the profile the tyre makes on the road (which will affect it's grip). As you increase the load the tyre will spread out at the bottom where it contacts the ground. To avoid this, increase the pressure to maintain the correct profile. You should keep your tyres correctly inflated depending on the load - i.e. if no longer under load, you should deflate them accordingly. This is as much to do with the logetivity of the tyre as it is your safety.

saintjanet

Incorrect tyre pressures can result in uneven tyre wear and increase petrol consumption.Always check them when cold ,as hot tyres can give a wrong reading,oh and also be aware that some tyre pressure guages are not very accurate so buy a good one or find a good garage that has one.

wolfehouse

can you please tell me- if i use the local petrol station's tyre compressor thingy (my local sainsbury has a digital one)
does it release air to lower the pressure (as well as increase it) or do i have to do it some other way ?(if so how do you do it?)

vikingaero

Just take out what you put in.

If your tyres need 32psi and you add 5 psi for the extra load, then reduce the pressure by 5psi only even though your tyres may read 40psi. If your hot 40psi tyres are relieved of 8psi of air to get them to 32psi then when the tyres cool they will be underinflated.

joshm_2

To manually release pressure from a tyre, use your fingertip or something thin like a match or biro to hold down the central pin in the tyre's valve. I'm not sure if the machines are capable of defaltion as well as inflation (you would have thought it's a good idea, though!?).

For anyone wanting a decent footpump, I can highly recommend the Michelin twin-barreled one. I tired of the cheap, innacurate and flimsy ones from Wollies etc and splashed out £20 on this. It is excellent (I know, getting excited about a footpump is not normal!).

highguyuk

wolfehouse wrote: »

does it release air to lower the pressure (as well as increase it)

Simply put, yes.