Tyre Pressure.

[CHRISCHANCE]

I didn't like the way my ML55 AMG handled at speed, especially on bendy roads. I visually checked my tyres but couldn't really see any difference.

I bought one of those LED tyre pressure gauges and found the front n/s was 26psi and the o/s was 29psi. The rear n/s was 20psi and the o/s was 36psi.

I went to my local petrol station and pumped my tyres to: Front 32psi and Rear 36psi.

I know this is slightly over the top but I think because it is such a heavy lump it is justified. It certainly drives like a dream now and handles the bends like its on rails.

The tyres are Gross Contact Continentals: 295/45/ZR20.

What do you think: Too much or not enough?

Best,
Chris.

 

[BTB 500]

What are the tyre pressures meant to be?

 

[Rashman]

It's good that you found out how different the tyre pressures were and addressed it.

I check my tyres everytime, before I head out.

I would have thought you should have more psi upfront though.

32 psi does not sound enough at all.

On mine, I run 35 psi on all tyres.

 

[John]

I run 36 all round on mine and check them once a month.

I see plenty of cars where the tyres are not pumped up enough and that screws your handling, mpg and could get too hot at faster speed and fail - not to mention the damage to the tyre - particularly the sidewall.

 

[CHRISCHANCE]

Thanks for the replies.

There are various tyre pressures printed on the inside of the petrol cap cover. They range from 29 front 32 rear with just the driver, to 32 front 39 rear with a full car. There are two intermediate readings but I'm not Teutonic enough to be ****d with that.
I ran my Pajero (another hefty lump), for 8 years with 42 all round, no probs. So I think I'll go like JohnEboy and go 36 all round. That is, unless somebody with more knowledge has something else to say, which may well happen because these figures are probably for Autobahn speeds, where if I remember correctly, there are no speed limits on many stretches of Autobahn.

 

[joecash]

i would check tyre wear across the tread weekly to make sure tyre wear is even

 

[markjay]

The handbook says that the pressures listed are recommendation only and that you can run the car on the higher figures all year 'round even when the car is not loaded (as long as you don't mind the slightly harsher ride).

Tyre fitters say to always use the higher pressure figure because it minimises tyre wear.

When I was a young lad it was common knowledge that for a 'sporty' ride and more responsive suspension you should keep the tyres at 2-3 psi above the highest figure given by the manufacturer.

Hope this helps....

 

[BTB 500]

As above, slightly higher pressures are OK.

Be aware that if you check them after a drive they will read high (due to the heat in the tyres). Also gauges vary in accuracy!

 

[Rashman]

Spend a bit of money on a decent digital gauge to use alongside your pump.

Shouldn't really trust analogue gauges on manual pumps, for example.

 

[BTB 500]

Here's an Auto Express group test of tyre pressure gauges - it's a few years old now but has reviews of 12 different ones:

Tyre pressure gauges | Auto Express

I got their 'best buy' one (which happened to be analogue rather than digital) for about £9 delivered. Before that I had a digital one that wasn't very accurate and also ate batteries!

Main thing is as Rash said - don't trust the gauges on pumps/compressors/air-lines. I over-inflate a bit based on my compressor reading then let air out to set the pressure accurately using my hand-held gauge.

 

[Rashman]

.... I over-inflate a bit based on my compressor reading then let air out to set the pressure accurately using my hand-held gauge.

Same here.

Best way.

 

[BTB 500]

And then of course polish the tyre valve covers

 

[rhud]

The only time in my life that I have departed from filler-cap tyre pressures is with my current car, a so-called BlueEfficiency (manual) variant of the W169 A Class. MB specify 32psi front/38 rear,compared to 29 all round for the non-BlueEfficiency (auto) version.

They are trying to bolster somewhat exaggerated claims about improved mpg with high pressures which improve rolling resistance. But it just wrecks the ride. Tyres on both versions are exactly the same.

 

[Rashman]

And then of course polish the tyre valve covers

Of course!

And where possible, get chrome or polished valve neck sleeves to complete the look.

 

[Dieselman]

Here's an Auto Express group test of tyre pressure gauges - it's a few years old now but has reviews of 12 different ones:

Tyre pressure gauges | Auto Express

I got their 'best buy' one (which happened to be analogue rather than digital) for about £9 delivered. Before that I had a digital one that wasn't very accurate and also ate batteries!

I have the Race-X gauge as well. Is it accurate...who knows, but it appears to be and consistent.

The problem with digital gauges is they use the battery voltage as the comparison, so do tend to vary as the battery loses power.

 

[sjmaxwell]

The only time in my life that I have departed from filler-cap tyre pressures is with my current car, a so-called BlueEfficiency (manual) variant of the W169 A Class. MB specify 32psi front/38 rear,compared to 29 all round for the non-BlueEfficiency (auto) version.

They are trying to bolster somewhat exaggerated claims about improved mpg with high pressures which improve rolling resistance. But it just wrecks the ride. Tyres on both versions are exactly the same.

Not to mention wearing he centre of the tyre out!

 

[CHRISCHANCE]

Thanks for the feedback and interest.

I will go 36psi all round and monitor the tyres. I check my tyres often (habit), but as sjmaxwell mentions the centre of the tyre, we all know an over inflated tyre will wear rapidly at the centre so I will pay particular attention there.
Regards,
Chris.

 

[ringway]

I have the Race-X gauge as well. Is it accurate...who knows, but it appears to be and consistent.

The problem with digital gauges is they use the battery voltage as the comparison, so do tend to vary as the battery loses power.

Had to bump this so I could read the whole thread. I could only find reference as a single post.