Are these tyre pressure readings adequate?

G

gebbel

Registered User
Messages
1,005
Today I checked the tyre pressures on my car. Here are the readings:

Front left: 28.9 PSI____________ Front right: 34.5 PSI
Rear left: 29.8 PSI ____________Rear right: 30.1 PSI

In terms of optimizing fuel economy, are the above readings good or bad? Should the front right be deflated a little to match the other 3 tyres? Or should they all be inflated? The tyres are not the same on all 4 wheels.
The car is a 2005 A4 with 18" alloy wheels.
Thanks.
 
I'd have thought the front 2 should be matching each other to within a few decimal points PSI
 
Front two the same and back two the same for me with front and back usually at different recommended pressures on motors I have had. See [broken link removed] for guidelines.
 
Are you sure the irishmotoring figures are still correct? They have Ford Sierras and Granadas but no Focus - they could be out of date (do tyre pressure figures go out of date - who knows?).

To OP - your car's manual should tell you the correct pressure.
 
Look inside the fuel filler flap - it will give you the manufacturer's recommended pressures for each load configuration.

I'd suggest something like 34 psi front and 32 psi rear, if there is a big diesel lump in the front. With 18" wheels & tyres you may need to reduce the pressures slightly for ride comfort.
 
if in doubt jsut set them all to 30, you should not have the LHS and RHS at differing amounts.
 
I have a label inside my fuel cap telling the pressure, its 30 psi

Sometimes you can find it on your tyres and also in your manual
 
There should be no difference Left to Right on the same axle.

An A4 should have the pressures on a panel on the back of the driver's door opening, it's probably in the manual too. It'll give you the pressures for light and heavy loading.

Not sure there's any point quoting pressures to decimal points given the poor accuracy of many gauges.

SSE
 
gebbel said:
Front left: 28.9 PSI____________ Front right: 34.5 PSI
Rear left: 29.8 PSI ____________Rear right: 30.1 PSI

In terms of optimizing fuel economy
Click to expand...
I'd inflate the other three tires to 34psi or more. The low pressures specified on the door placard are for comfort. For economy you'll have to inflate your tires a good bit more than 32. Check your tread depth before you do this and then check it a few thousand km later to check for uneven wear.

ollie
 
ollie323 said:
I'd inflate the other three tires to 34psi or more. The low pressures specified on the door placard are for comfort. For economy you'll have to inflate your tires a good bit more than 32. Check your tread depth before you do this and then check it a few thousand km later to check for uneven wear.

ollie
Click to expand...

That's bad advice, the center of the thread will wear quicker then the side and you will have less grip due to the higher pressures, car will be very uncomfortable and skittish on the road.
If you are that interested in fuel economy ditch the 18" alloys ad fit lighter 16" wheels.

P.s. It's not a good idea to have two different tyres on the same axle, especially on the front axle, braking performance will be uneven.
 
Agreed on the different tyres. Braking characteristics will be diffreent and during hard braking a tyre might let go sooner than the rest, throwing the car into a spin.
Re; extra centre wear due to higher pressures, that isn't always the case. In the case of a 205/55R16 michelin i have, yes, it did wear more but at 32 psi, it wore a lot more at the shoulder of the tyre. In the case of a single 195/55R16 Bridgestone it didn't wear unevenly at all, right up to the sidewall max of 51 psi. In the case of a 195/65R14 firestone i have on another car, it didn't wear unevenly at all, right up to the sidewall max of 44 psi. Finally, in all the cases of inflation above placard pressure, grip was not affected in any condition. During the recent snow i was going up a steep hill in my yaris (without any wheelspin) while every other car on the hill at that time were literally stuck, unable to climb it or sliding down, trying to avoid sliding into the ditch.
All i'm saying is that the standard reply to what pressure you should use in your tyres is not always correct. Also, some tyres will wear more in the centre while at higher pressures and i have yet to figure out why. Incidentally, most if not all tyres will wear less in the centre and more at the shoulder while at placard pressure. (usually 32 psi). Hava a look at this picture. It was of a tyre that spent its life at placard pressure of 32 psi.http://techno-fandom.org/~hobbit/cars/tpms/tn/treadwear.jpg
Here is a very informative thread on the subject: [broken link removed]
And finally here:
The examples of tyre wear i gave above are from experience with my own tyres. I haven't based any of this on hearsay .

ollie
 
You must log in or register to reply here.
Back
Top