Tyre Pressure

[uksweetheart77]

We took our Fabia to a garage this morning for a minor service. The petrol cap says that the tyre pressure should be 30PSI, however according to the checklist, the garage has inflated all of the tyres to 35PSI and the spare to 40PSI. Why would they inflate them to over the recommended amount and should we deflate them to the correct pressure? Thanks.

[KenONeill]

@uksweetheart77 - The correct pressures for the tyres should be stated on a sticker either in the fuel filler cover or inside the driver's door shut. If that says "30PSI" there is no good reason for varying from that by more than 10% (3PSI), and even that variation means a correction for a specific make of tyre.

 

The only reasons I can see for the over-inflation you're quoting on the road wheels are that the garage air line isn't correctly calibrated, your gauge isn't correctly calibrated, or the garage staff don't care. Was there any sign of edge wear before the service?

 

As for the spare, many people do over-inflate those and let them down a bit when fitting, but 40PSI is still too high; certainly bring that down to 36 or less.

[uksweetheart77]

@KenONeill We haven't checked the pressure ourselves using the air machine we normally use at our local petrol station. The pressure I'm quoting for the tyres was written on a sheet of paper by the garage that did the service for us. The car is only 1 year old and the only wear is to the front tyres. They've written that the back tyres have a 7mm depth (outer, centre and inner) and the front tyres have 6mm. I've attached a pic of the sheet.

Edited 10 April, 2019 by uksweetheart77

[ColinD]

Is it possible they didn't inflate the tyres?

 

Just wondering if the local air tool you use is out.

 

If both are out, there isn't much in it.

 

They may of course of inflated to 35. If the new ones are that level, a slip of thought, routine etc.

 

One other minor factor is tyre temp,but that would not account for 5psi.

[Ootohere]

Filling Station Tyre Inflation devices you pay to use are calibrated.  There are major issues if they are out / incorrect.

 

Main Dealership / Garage / Tyre Fitting Centre Tyre Gauges should be calibrated, for insurance and H&S reasons.

Big trouble in Little China if they have duff devices, and also if employees are say they checked or adjusted and never did. or over inflate or leave over inflated as often happens at PDI's., Demonstrators, Hire Cars etc.

 

So any driver should have a good tyre gauge and check actual pressures themselves, or go to a filling station with a device.

and set when collecting car new, hired, serviced, 

it is basic stuff.

If someone does your tyres, inspects, checks, adjusts pressures,  ask what they are at, or look at the report then check them and reset your TPMS, because maybe they never did.

But you need an accurate Pressure Gauge.

Edited 10 April, 2019 by Skoffski

[26DIPP]

There is no absolute "correct" tyre pressure as recommended by the manufacturer. They usually give you a pressure that they think provides a comfortable drive.

I attended a driver safety training and their advice was 10 - 15% over recommended. I have been doing this ever since. You have a slightly harder but not uncomfortable ride and the car is a little less wallaby like pus I noticed that tyres last longer.

[uksweetheart77]

Thanks for your replies.

 

Just over a week ago, there was a slow puncture in one of the tyres and we got it fixed at a tyre fitting centre. I guess it's possible that they were the ones who over inflated the tyres but that doesn't explain why the garage today didn't then deflate them a little. I also can't imagine the tyre fitting centre bothering to inflate the spare to 40PSI.

 

Would you guys recommend deflating them to 33PSI maximum or should we just leave them this one time?

[Ootohere]

Many Tyre fitters / repairers inflate a tyre high and then let down to 35PSI and do not check what the recommended pressures are.

 

There are customers that get cars serviced that complain if the pressures are adjusted on a car, but the technician / fitter has put the pressures in writing for you to know, 

so job done.

 

?

What is the recommended pressure range for your cars tyres with different loads as shown on the Filler Flap?

 

It can not just show 30psi.

 

?

Is there not something along these lines on the sticker?

Edited 10 April, 2019 by Skoffski

[uksweetheart77]

Without looking right now, I know it's 2.1 bar (30PSI) for half load and I'm pretty certain it's 2.2 bar (32PSI) for a full load. We only ever have 2 people (maximum) in the car and a bit of shopping in the boot.

Edited 10 April, 2019 by uksweetheart77

[Ootohere]

Best set to the recommend pressures for your tyres.

I would leave the Spare Tyre at 40PSI and if you need to fit it adjust the pressure, or set it correctly and always check when doing the other 4 tyres.

As it is the spare is a different size from the other 4, but you never want to go for the spare to find it is underinflated.

[KenONeill]

@uksweetheart77 - OK, based on the other posts since I was last on, I suggest you buy a BSI marked pen gauge, about £5 from Halfords, and stop relying on garage air lines for actual pressure! The compressor they're connected to typically gives around 200PSI.

[uksweetheart77]

38 minutes ago, KenONeill said:

@uksweetheart77 - OK, based on the other posts since I was last on, I suggest you buy a BSI marked pen gauge, about £5 from Halfords, and stop relying on garage air lines for actual pressure! The compressor they're connected to typically gives around 200PSI.

 

Thanks, @KenONeill - I was looking at gauges online this morning as I was already considering that. 

 

Went to deflate the tyres and our local petrol station machine had the spare tyre at 37PSI and the rest at 32PSI so all 3PSI less than what the garage quoted.