[Tracie]

Just been browsing through this tyre section and have noticed the big differance that ppls prefer to use on tyre pressure.

I have 17" runflats and tend to have them around 32-33 psi.
Some threads I have read show 35+ psi all round..

My question is this Is there a very big differance to handling and ride quality if a higher psi is used and is it recommended to do so?

[SteveM3]

You have your tyre pressures set correctly for a starting point. Now if you are serious
about getting the correct pressure ignore what other people are using and check your
tyre wear, you are aiming for even wear across the tread. That way your tyre pressures
will be correct for your driving style and your car/tyre combination.

Being lazy I've cut and pasted below some earlier comments I've made.

Trading comfort for handling or vice-versa doesn't really work using tyre pressures. You'll
wear out the outside edges if you aim too low and wear out the centre if you aim too high.

Tire pressure needed varies due to production tolerances in tyres, weight of the car and
driving style. It is also influenced by temperatures and the fact that guages are rarely pin
point accurate. However in the long term there is a real simple way to tell. Get a tread
depth guage and check your tyres every few thousand miles. If the tyre is losing tread
fastest on the outside your tyre is underinflated and you should try a higher pressure. If
the tyre is losing tread fastest on the inside your tyre is overinflated and you should try a
lower pressure. If tyre wear is uneven side to side then get your suspension checked.
When you have even tyre wear it means the whole tyre is being used which will gives
you the best mileage and the most grip .

[obehave]

Steve is absolutely correct. The question missed though is handlling difference.
Yes it does make a difference.

I run 35F and 37R and I like the balance and tracking better than just 35 all round. It's a personal preference and not a recommendation.

[Tracie]

Thanks guys

[SteveM3]

Quote: Originally Posted by obehave

I run 35F and 37R and I like the balance and tracking better than just 35 all round. It's a personal preference and not a recommendation.

That's interesting. Owning RWD cars for the previous 15 years I've been running a higher
rear than front pressure setup and had assumed this would stop or be reversed when I
changed to FWD. I have been surprised then that 30F/33R has been best for me.

[STS2]

That is weird SteveM3. Was all your RWD cars during that 15yrs understeering, or did just like to have the tail hanging out ?

[SteveM3]

Quote: Originally Posted by STS2

That is weird SteveM3. Was all your RWD cars during that 15yrs understeering, or did just like to have the tail hanging out ?

No understeer, oversteer very rare but lots and lots of full throttle exits from roundabouts.
Roundabouts are the best part of UK motoring . I destroyed a set of 225/50-16
Yoko's in less then 8,000 miles but realise now this is mild. See stories of Works 18"
wheels and dunlops.

[Haggi]

30 psi all round works for me but ive got 16's

[Ian Kuah]

Quote: Originally Posted by Tracie

Just been browsing through this tyre section and have noticed the big differance that ppls prefer to use on tyre pressure.

I have 17" runflats and tend to have them around 32-33 psi.
Some threads I have read show 35+ psi all round..

My question is this Is there a very big differance to handling and ride quality if a higher psi is used and is it recommended to do so?

Higher pressures also equal harsher ride. You can play with front-to-back pressures for fine tuning like you would with different diameter anti-roll-bars. But bear in mind that there is a difference between less understeer and more oversteer.

6psi higher in front because fwd cars are nose heavy. High pressures at the back equals twitchy and a nasty tendency to oversteer when you lift off in a fast bend.

Try 30psi front and 24psi rear for a car on 16-inchers and add 1 or 2psi as you go up in wheel size. Ultimately, you never need more than 33psi in the front of a car that only weighs 1,050kg. A 1,900kg rear-driven Mercedes SL55 AMG with 500bhp only needs 35psi with 19-inch wheels and 35 profile tyres!

[obehave]

Quote: Originally Posted by Ian Kuah

Higher pressures also equal harsher ride. You can play with front-to-back pressures for fine tuning like you would with different diameter anti-roll-bars. But bear in mind that there is a difference between less understeer and more oversteer.

6psi higher in front because fwd cars are nose heavy. High pressures at the back equals twitchy and a nasty tendency to oversteer when you lift off in a fast bend.

Try 30psi front and 24psi rear for a car on 16-inchers and add 1 or 2psi as you go up in wheel size. Ultimately, you never need more than 33psi in the front of a car that only weighs 1,050kg. A 1,900kg rear-driven Mercedes SL55 AMG with 500bhp only needs 35psi with 19-inch wheels and 35 profile tyres!

Maybe but both of thoses pressures are below or well below recommended pressures.
Low pressure causes excessive sidewall heating. Remember the Ford Explorer rollover, tire blow out problem? That was under inflated tires.

Your best gauge of pressure is tire wear. If you're willing to sacrifice a bit of tire life you can modify pressure from that baseline.
Like I said I run 35F and 37 R and rotate every 3-5K and my tire wear has been fine.
NOt sayig my way is the only way but recommending tire pressures 9psi under what BMW suggests and below what is recommended by Dunlop and Bridgestone ( my old runflats and my current street tires) might need to be rethought.

[MarkW19]

Although I've recently got new tyres a couple of thousand miles ago (Toyo T1S Proxes) on my Cooper (17" S-Spokes), my car seems to skid around corners instead of gripping to them, even at just medium speeds! I seem to remember it handling better than this and being a lot more sure-footed.

Also, the steering seems lighter and less responsive (ie. you have to turn the wheel more to get more of a response), I remember it being more directly, heavier and sensitive before.

Currently, my tyres are set at 30psi for the fronts, and 28psi for the backs.

Does anyone have any suggestions to the psi (or anything else!) I should use to cure the above problems?

[obehave]

Quote: Originally Posted by MarkW19

Although I've recently got new tyres a couple of thousand miles ago (Toyo T1S Proxes) on my Cooper (17" S-Spokes), my car seems to skid around corners instead of gripping to them, even at just medium speeds! I seem to remember it handling better than this and being a lot more sure-footed.

Also, the steering seems lighter and less responsive (ie. you have to turn the wheel more to get more of a response), I remember it being more directly, heavier and sensitive before.

Currently, my tyres are set at 30psi for the fronts, and 28psi for the backs.

Does anyone have any suggestions to the psi (or anything else!) I should use to cure the above problems?

Low pressure will allow greater sidewall flex. Increase slip angle and delay turn in. To me your pressures are low. Step up to the baseleine of 33psi all round and see if you like the difference. Also remember it's cold so starting pressures may be even lower.
Tire pressure is one of the few free mods you get to play with. So you may as well play and have fun.


Can't help with the other bits though.

[William Courant]

32 psi all around on my 15s set with a digital gauge. Rides great, handles great and even wear

[DeadCanDanceR]

I have 16s with Runflats, and I was told that 34 psi is the suggested pressure for these! Have others been told the same thing?

[MarkW19]

Cool I'll have a mess about tomorrow then!

[obehave]

Quote: Originally Posted by DeadCanDanceR

I have 16s with Runflats, and I was told that 34 psi is the suggested pressure for these! Have others been told the same thing?

My '02 was suggested at 33psi. Weight of options may make a difference. I never thought about it but if you add sunroof, xenons, etc you have a heavier car than I have. MIne's a stripper.
That might make a difference.

[ThumperMCS]

My 05 says to keep them at 38, yet i've rarely seen anyone on here with pressures that high for normal driving. Maybe i'm mistaking, but I could have sworn the door says 38psi...hmm

[PM_]

My Cooper's got 35psi front and 33psi rear, seems to be the best compromise for me in terms of handling/grip/comfort

Used to be 32-33psi all round... the tyre squeaks and understeer quite a bit earlier, hence the change

[MarkW19]

PM: What wheels/tyres?

[MarkW19]

Is your steering fairly heavy then? Isn't the ride too hard??