Any tyre pressure experts out there?

[tonyg]

The car is starting to loosen up now and I've come to the conclusion that the official tyre pressures are too hard (same as the last car).
I'll probably try the suggestion that Kayfur give me for the old car (23 front,25 rear).
I'm probably not a good enough driver to work out the best pressures by myself, but if i try what difference should i expect when increasing/lowering either (or both)?
any help appreciated

Tony.

[graeme]

You can work it out yourself with a cheap infra-red thermometer.

Like this:

http://www.amazon.co.uk/Benetech-Profes ... hermometer

or this:

http://www.amazon.co.uk/Fluke-Intrinsic ... hermometer

Or something in between

Go for a spirited run, then take 3 temp readings across each tyre, inside, middle and outside. In an ideal perfect setup for the type of driving you just did, they should all match. If the middle is higher, you're over-inflated. If it's lower, you're under-inflated. If the inside is higher you're running too much +ve (EDIT: I mean -ve) camber (but that's normal for road use... nobody leans on the tyres that hard on public roads). If the outside is higher, you probably need the geo looked at.

The racers have more experience with this setup and can probably offer tips.

[mckeann]

You can work it out yourself with a cheap infra-red thermometer.

Like this:

http://www.amazon.co.uk/Benetech-Profes ... hermometer

or this:

http://www.amazon.co.uk/Fluke-Intrinsic ... hermometer

Or something in between

Go for a spirited run, then take 3 temp readings across each tyre, inside, middle and outside. In an ideal perfect setup for the type of driving you just did, they should all match. If the middle is higher, you're over-inflated. If it's lower, you're under-inflated. If the inside is higher you're running too much +ve camber (but that's normal for road use... nobody leans on the tyres that hard on public roads). If the outside is higher, you probably need the geo looked at.

The racers have more experience with this setup and can probably offer tips.

Spot on, except I think you mean negative camber if the inside is hotter?????

[graeme]

Spot on, except I think you mean negative camber if the inside is hotter?????

Of course I did. I was just checking if you banged your head.

[alicrozier]

One slight modification (to take out camber effects and maybe more suitable for road driving) is to look for an even temperature gradient across the profile.
e.g.
65 60 55

65 65 55 = too much pressure
65 55 55 = too little pressure

None of this is 100% accurate and lots of other contributing factors but good enough to work to.

[graeme]

Oh, that's good Ali. I like that.

[C7Steve]

One slight modification (to take out camber effects and maybe more suitable for road driving) is to look for an even temperature gradient across the profile.
e.g.
65 60 55

65 65 55 = too much pressure
65 55 55 = too little pressure

None of this is 100% accurate and lots of other contributing factors but good enough to work to.

Are you still taking it on the Frolic?


Steve.

[alicrozier]

Yup, have infra red thermometer in my tool bag. All welcome to borrow.

[C7Steve]

Getting excited now.


Steve.

[martins]

I will be putting in a protest to the Mods soon.

Every other thread on here seems to end up being hikacked by those going on FROLIC. Please stop this as it continually reminds me that I am NOT going on FROLIC and instead have to stay in Aberdeen for reasons now unknown. I did suggest to HWMBO that I take Andy's spot . This was met with a death stare followed by a 5 minute lecture re daughter moving out, flat purchase, morgage to arrange and various other trivia....

All I have to look forward to is KH on 05 Sept when I will no doubt have to listen to all the stories about........you guessed it.....FROLIC.....

[Kinger]

I will be putting in a protest to the Mods soon.

Every other thread on here seems to end up being hikacked by those going on FROLIC. Please stop this as it continually reminds me that I am NOT going on FROLIC and instead have to stay in Aberdeen for reasons now unknown. I did suggest to HWMBO that I take Andy's spot . This was met with a death stare followed by a 5 minute lecture re daughter moving out, flat purchase, morgage to arrange and various other trivia....

All I have to look forward to is KH on 05 Sept when I will no doubt have to listen to all the stories about........you guessed it.....FROLIC.....

Martin, I thought you were the boss. Give her a kiss on Thursday morning and say see you on the 24th.........Bye !!

[martins]

I was wondering how long it would take you to come along Kinger......tried the kiss and go before with work and it does not really work....I have however got a provisional kitchen pass for a week away in the car next year[THUMBS UP SIGN][THUMBS UP SIGN][THUMBS UP SIGN]

[tonyg]

Back on topic

Thanks for the help guys.

I have to admit i was expecting something like if you go lower on the front it will oversteer/understeer more/less and affect the balance in this way, but it's about getting the tyres working correctly that's fine by me.

[Scotty C]

I prefer to work on pressures when there hot. Because everyday is different. I've seen me using pressures as low as 22 when cold. This is mainly for track use but should also work out on road. Go out for a spirited blast and pull over and try your pressures.

[gambler]

Especially for track, get some heat into them and then adjust the pressures from there. For the road, i just make sure that they are round