simple really

are you supposed to check your tyre pressures when the tyres are cold or when they are hot?

 

Cold!

The pressure expands with heat, thus you will get a false reading.

Martin

 

but that would mean that when the tyres are "up to temp" they will have mroe pressure in them than when you checked won't they?

so how does that work?

watching a motoring program on the telly the other night they said you should check the pressures when hot to factor into the equation this heat expansion

 

Always cold afaik.

 

Yes they will have more pressure in them when up to temperature, but i suppose the tyre / car manufacturers take this into account when they are doing r&d and thus give their recommendations for tyre pressures factoring this in.

If you were to top them up warm you would never be able to know how warm the tyres were so i guess would never be able to accuratly consistantly get them the same.

 

so how do f1 teams and the like check the pressures in their tyres?

do they put them in cold? hot? depending on what the temp is on the track?

i know your normal car won't need this sort of stuff going on so just wondering is all

 

Track use is different. Pressures will vary from track to track depending on layout and from tyre to tyre depending on load. Tyre pressure monitoring systems as in run flat technology.

 

cold, they dont get hot with road use......

 

F1 teams use nitrogen, same as aircraft. this expands less than air when heated so there is no real difference. and on aircraft i have always done tyre pressures when cold

 

They do if there is not enough air in them in the first place

 

So will Kwikfit, if you pay them for the privilege , a kind of pointless gimmick for the road really.

Martin

 

but only if you buy new tyres from them

 

Definately a pointless gimmick for road use. but there are plenty of idiots that believe that if race teams do it, so should i.

 

Observe use is different. Requirements will vary from track to keep track of depending on structure and from wheel to wheel depending on load. Tire pressure monitoring systems as in run flat technology.

 

How cool is that spam, looks like its copied and mashed up my post lol.

 

Lol!!!

I didn't even realise it was spam

Seems to be a lot of it going on these past few days

 

Do them from cold. However I've tried a few different home air pumps and you'd be surprised how far off the gauges read when comparing to a calibrated gauge. I bought a brand new foot pump, inflated tyres to the manufactures spec of 36psi, checked with a calibrated gauge and I only had 31psi. checked with another shop bought gauge I had lying about and I got 38psi. If you want your tyre pressures to be spot on then get your hands on a calibrated gauge and get it checked a couple of times a year, ours at work were done every 3 months.

 

I normally use the digital ones, but then how do you know that your tyres are hit or cold when you have to drive 3 miles to get the pressures checked?

 

You over inflate them by a couple of psi, drive home, wait for them to cool then check with your calibrated gauge, lowering the pressure slightly as required. Or buy a pump for a tenner and do it at home lol

 

on a road car just do them cold as normal.