Suprising Tyre Pressures

[s4-matt]

Is it just me or are the recommended tyre pressures surprisingly high. Both my current cars have 18's and both have a recommended pressure of 39psi and 42psi fully loaded (granted the a3 is only 39 and 42 on the fronts).

I went to Sainsbury's at lunchtime to pump up the tyres on the a3 and all were 28psi. Now I new they needed doing but certainly didn't look what you would call flat, and have only been on the car for about a month. I've also pumped up the s4's a couple of times using the same digital pump to 39psi and within a week or so gone back to find they will all be down at 32psi???? Do people really pump up their tyres every week and if they do does it make that much difference to fuel consumption and tyre wear?

Anyone else had the same thoughts? Or do I have to much time on my hands?

[DropKickMurphy]

hi there S4-Matt,

are the tyres low profiles? if so i would assume that they need to be harder than regular tyres as they need to soak up bumps better, you wouldnt want to hit a pot hole and damage the rim.

one quick suggestion - have you got a tyre pressure guage? the petrol station ones are notoriously unreliable having been run over hundreds of times and been left exposed to the elements for years! i got a cheapy one which just serves as a double check for me once i have pumped my tyres up to what the petrol station guage claims is the correct PSI.

DKM

[gazza57]

hi there S4-Matt,

are the tyres low profiles? if so i would assume that they need to be harder than regular tyres as they need to soak up bumps better, you wouldnt want to hit a pot hole and damage the rim.

one quick suggestion - have you got a tyre pressure guage? the petrol station ones are notoriously unreliable having been run over hundreds of times and been left exposed to the elements for years! i got a cheapy one which just serves as a double check for me once i have pumped my tyres up to what the petrol station guage claims is the correct PSI.

DKM

I totally agree with DKM, the garage pressure gauges are as bad as +/- 20% which means a reading of 1.9 Bar (26.8 psi) could be as high as 2.28 Bar (32 psi) or as low as 1.52 Bar (21.3 psi).
I don't think any pressure gauges used for air at Garages are required to meet NAMAS (National Measurement Accreditation Service) calibration standards either if you pay for your air or if it's free yet over or under inflated tyres can pose a serious safety hazard.
Gazza57

[paulthefox]

carry your own gauge solve's the problem i carry 2 plus one for tyre depth

always be prepared

paul

[martin1810]

If you ever have to brake or corner hard in an emergency with a low pressure tyre you will know why they need to be pumped up. My wifes, non VAG, needs tyres pumping every week. I think it is because the alloys have become porous. It is why you often see truck tyre ripped to bits on motorways. One tyre on a twin wheel, looses pressure and in short order rips its self to bits.

[paul b]

My A6 with 235/45/17s all round takes 30psi which seems reasonable.

My T5 however, takes a ridiculous 50 something psi on the front and 62 on the rear!

I do pump them up to such pressures, but find myself shaking whilst pumping them up to such pressures, thinking "if this tyre just explodes, it'll have my head off..."

[s4-matt]

My A6 with 235/45/17s all round takes 30psi which seems reasonable.

My T5 however, takes a ridiculous 50 something psi on the front and 62 on the rear!

I do pump them up to such pressures, but find myself shaking whilst pumping them up to such pressures, thinking "if this tyre just explodes, it'll have my head off..."

I must admit similar thoughts go through my head too!

[Borab0y]

The T5 is a commertial vehicle and can carry alot more weight than a car.
The greater weight and more load the vehicle can carry the higher the pressure will be in the tyre to support it.

They will be made stronger to take the extra weight and pressure, It should say on the sidewall what the maximum pressure the tyre can take.

And dont forget the recomended pressure for the tyre is when cold without any driving being done on it.

Try setting the pressure first thing on a hot morning then taking it for a swift drive along some twisty roads and recheck the pressure, you'll be surprised at how much it goes up.

[martin1810]

Always pump my old LT35 van up to 50psi. They still don't look over inflated. I did pump my sons bike tyre up with the compressor one day. Made hell of a bang when it exploded. oops !!!