What Psi?

[OzBoy]

I have a 2008 X and was wondering if anyone can tell me the best tyre pressure to use on front and back as they are different sizes or will it not matter? Thanks in advance.

[khoala]

it would depend on your style of driving, tyre/diameter and width combo

there is no standard figure, best to start say 5psi off the maximum and every few days drop a psi and see how that goes.

i know with my other car, i have 225/40/18 max psi is 51 but i run 32psi cold, rears were 235/40/18 51psi max, i ran 28psi cold

just depends what you feel comfortable with

[Bluey]

Ozboy

Check the manufacturer guide inside the drivers door jamb. That will give the best ride comfort and tyre longevity.

If you like a spirited drive, or faster, then about 5psi more all round would be a good start.

[OzBoy]

OK an extra 5psi all round....like that "spirited" will use that with my wife when she tells me I am driving too fast....Nah darlin it's just "spririted"!! :P

[last1]

The recommended level indicated in your car manual covers all the different tyre combinations. As Bluey already suggested, the recommended level is also the best all-round pressure. It will generally give you a decent ride, good fuel economy and less tyre wear - so long as you use your car as an average person does. ie many short trips, a few longer ones, the weekly boot full of shopping, driving to work alone but having all the family in the car on the weekends etc.

As far as PSI goes - the aim of the game is to get the the tyre's tread to sit on the road the way the manufacturer designed it to sit.

Now, bearing in mind that inflating too high or low is very bad: Higher inflated tyres will have less of the tread pattern on the road and thereby reduce road traction and increase wear in the centre of the tyre tread. Less tread on the road will however assist rolling resistance and reduce fuel consumption.

Lower inflated will result in too much of the tyre's side rubber on the road surface and will again reduce traction as well as accelerate wear on the sides of the tyre. Less pressure will also lead to more rolling resistance and higher fuel consumption.

Increase the PSI if most of your driving involves carrying passengers in the car or heavy stuff in the boot.

Increase the PSI if most of your driving is highway/freeway.

Decrease the PSI if most of your driving is done on really bad roads/off road (keeping the speed down as well!)

If confused - read your manual and use the recommended PSI. And buy a decent tyre pressure gage (most of the ones at the servo don't read correctly!!!!!!!!!).

Hope this helps.

[Sapphire Cam]

Good to see everyone is on the money here.... about 3-5 psi above manufacturer recommendation is about spot on. Our instructors at the advanced driver training course I did at Sandown Park a few years ago kept stressing that that was what a tyre is designed to operate at, but all manufacturers drop the rating that much universally, so as to give their vehicle a slightly smoother ride (you'll find that the cars for test driving invariably will have even lower pressure!).

So I run my Prestige at 38 F/41 R (instead of recomm. 35/38). Over the life of the tyre, an additional 3-5 psi should get you up to 10k more mileage, and you'll get a little bit better cornering (as there will be less flex/roll in the sidewall of the tyre). Its also a safer option, as a bit more pressure opens up the tread in the tyre and stiffens the sidewall