optimum tyre pressure?

[doug2.0]

ive got a set of eagle f1's 50profile on the williams and it says 51psi max, they were running at 30 before but didnt look too low, i put em up to 45psi and took it out, ride was so much harder and i lost it on a tight bend doing 15mph!! it was a greasy road tho and i managed to steer out of it (i kinda froze tho felt like a right incompetent idiot).

just wanted to know what the optimum tyre pressure is for best grip etc.

cheers
Doug

[Laine_16v]

32 front and 30 rear for started, then play around to find out what suits you best.

45PSI??!! no wonder you lost it going round a bend at 15mph lol.

[drsmith1979]

lol @ 45 psi!

i run 32 all around in most weathers, sometimes a touch less in the rears in wetter weather, all depends on whos in the car and what you are doing, 45 psi is too much imo, not enough give and you run the risk of having the tyres 'dome' out in the middle of the tread thus reducing rubber contact with the road

[doug2.0]

i know a decent amount about cars and do a lot of work myself but tyre pressure is just summat that ive never been told whats right, (i think on my old tyres it told you, and i had a hunch that it was around 30-35 but they were smaller profile so it thought it may have been different)
so i looked at the max (51) and put em to 45.
anyway cheers for the help ill go let em down now before i kill myself! :roll:

[drsmith1979]

just remember that pressure is proportionate and isn't anything to do with volume, so a large truck tyre under 45psi is the same as a small tyre with 45psi etc... anywhere from 30-35 is about right....

[Lunner]

No but it has to do with the surface area of the tyre....psi = Pounds Per Square Inch

[drsmith1979]

true but just because a tyre has a greater surface area doesnt make the pressure any greater than that of a smaller surface area tyre... it may take 20litres of air to create 45psi in a large tyre, but only 5 litres in a small one, the pressure exerted by the compressed gas is exactly the same as the pressure exerted by the larger wheel, its just exerting it over a larger area and thus requires more volume to reach.

[Lunner]

The smaller the tyre volume and surface area the higher the pressure needed.....hence why push bike tyres are inflated to about 45 psi, and car tyres to about 30

[drsmith1979]

lol i get your point, but that doesnt mean a bicyles tyre at 45psi is greater or lesser in pressure than a car tyre at 45psi... lol

[Lunner]

No its the same pressure, that wasn't the point i was making, my point was that lower profile tyres need a higher pressure than fat tyres, not alot mind, but 1-2 psi

[drsmith1979]

ahhh yes...yes you are quite correct lol

[BRUN]

most i have mine at is 34

usually 33/34 front and 33/32 rear

[katbloke]

mines usually 32 all round easy at the digital preset gauge machines

[white16valver]

Depends on tyres and weather conditions as well I've found.

I prefer 32/32 on 185/55 F1s when it's wet as it feels more planted, then I'll put them up to 33/32 or 33/33 when it's dry :)

I can notice a 1 or 2 psi difference through the steering - good really 8)

It amazes me how inert some cars are to different pressures, and how people just don't notice!

[titcharoony]

ya har, 32 all round has always been fine for me. 33 perhaps when dry i agree.

[talkingfish]

running mine on 29 at the front and 32 at the rear - I take it that's not correct then?

[Lunner]

Front wants to be higher pressure than the rear, most of the weight is on them

[ae]

Used to run 32 front & 30 rear. This gave good turn in and a very stable rear , even on the wet. Up to the owner, many people prefer different set ups.

Andrew

[rs250]

running mine on 29 at the front and 32 at the rear - I take it that's not correct then?

Thats what I use but round the other way.

[Lunner]

Also depends on the set up of the are, how low the front and rear are in respect to each other, and over all, as well as your driving style, best to play about and see what suits you best

[Bayliss]

it all depends on what tyres your using usually bcos mine on Hybrid are running at 39psi but thats bcos i use Vredstines and they require 30% more tyre pressure (as stated from manufacturer) but usually the going rate for the williams or generally any 195/50/15 tyre is 30 - 32 psi

Lunner sorry to tell you mate but your statement of fronts should be run higher is wrong unless u blow them up before they go on the car, bcos if you blow your tyres up whilst the weight is on them the tyre pressure should be set to 32psi bcos if you over pressure them you'll just run the centre of the tyres off (uneven wear). Usually you will find tyre centres (kwik fit etc) will blow your tyres up then balance and fit your tyre and if you don't check them until tyres are bald again you'll notice the outsides are worn more than middle this is due to under pressure (unless theres something seriously wrong with tracking then one side will be bald whilst other looks new)

[Lunner]

I've always run higher pressures on the fronts with no problems, alot of car manufacturers state higher pressures on the front do they not?

I know about if they are over inflated you';ll wear the centres down quicker, and likewise under inflated wear the sides down quicker

[Bayliss]

you'll onoly usually find that manufacturers reccommend higher pressures on diesels purely cos the motor weighs more, its not that often a newer car with a petrol engine it is reccomended they're run higher