How do you ‘Do’ Tyre Pressures?

[AudiNutta]

Hi Everyone,

After some advice / opinions on how to control tyre pressures. I have the live TPMS on my car, which is how I know temps / pressures all the time.

So obviously the common thing or recommended process is to inflate the tyres when cold. I’ve no idea why but my dealer inflated all tyres to 40psi on all 4-corners, I was told directly that they were recommending to all be the same.. needless to say I had a shock when I checked the door, 39 front and 35 rear is what is recommended for the staggered wheel setup with minimal load. I drove for 1500 miles like this because they hadn’t dropped, doh!

Anyway my local digital compressor is 3 miles away, during which time the tyres temps only climbed 2 degrees on 30mph roads only.
When sat and cold, my pressures drop to 36psi on the front and climb to 39.5psi when warm. My rears seem to be sat on 36.5psi when cold and warm.

Today when pulling out of the garage I had 36.5psi on the front, within a mile or so I had a warning that the car had detected a wheel change and the pressures had climbed from 36.5psi to 39psi, I’m not sure if that is why the car was led to believe there had been a wheel change?.. but the car has been driven like this for a week...
I’ve still not reset it, I checked the tyres when arriving at work and left the warning on inrentionally to remind me to check visually in the morning, but I’ve had no pressure loss according to TPMS.

I guess my real question is, shouldn’t we be checking tyre pressures when they are warm? Because as soon as they warm, the pressures climb. When I’m inflating them cold, the pressures end up showing 3psi under what I inflated them too according to TPMS.

I’m considering trying the Nitrogen, I believe I can get it done for a little under a fiver a corner locally and in theory the pressures will remain more consistent and I won’t lose any pressure over long periods of time?

Thanks in advance for some advice.

Matt.

 

[D0C]

Lol, the lengths some people go to, to control tyres pressures within a single psi! I'm probably too far the other way, but I never check my tyre pressures. 30 psi, 32 psi, 35 psi, I defy anyone who reckons they can tell the difference. For road use, providing they are 30+, you'll be ok, unless you're some kind of serious track or drag strip enthusiast.

 

[Alex L]

The whole nitrogen fill seems a complete con to me, seeing as regular air is circa 80% Nitrogen

 

[Phil3]

Nitrogen... don’t bother, I had this whole thing with my old GTR as what’s when’s ‘recommended’ in them... even the specialist I used to take it too used to laugh about it

 

[Ozmosis]

So what you are saying is that the TPMS is making you paranoid?

Remember that the front brakes get a lot hotter than the rears, heating the wheels and tyres and that'll give you a spurious reading.

As has been said, nitrogen is just another way for some people to make easy money, as air is almost 80% nitrogen...

The other question is: what is more accurate? The TPMS sensors or the compressor with digital display? Maybe you should go "old school"...

No surprises the dealer doesn't know about the tyre pressure labelling in the car...

 

[Arcam]

Always set "cold" unless resetting when used on track.

My staggered setup is 3.0bar and 2.7bar for normal running.

The fronts will always come up more due to (as mentioned already) heat from front disks plus the load transfers into them on braking plus cornering etc.

On track I normally see the fronts increase to 4 - 4.2 bar if I don't adjust and 3.2 - 3.5 on the rear.

I use a decent digital Michelin tyre pressure gauge, I don't find the tpms ones that accurate.

Sent from my SM-N910F using Tapatalk

 

[DW81]

Just out of interest how reliable is the onboard tpms. You could be chasing your tail for nothing relying on computers and microprocessors to work out tyre pressure when a quick visual check would suffice, if it looks flat pump it back, simples.

 

[DW81]

Nitrogen... don’t bother, I had this whole thing with my old GTR as what’s when’s ‘recommended’ in them... even the specialist I used to take it too used to laugh about it

****** nitrogen people will be putting helium in next to shave a few kilos

 

[SteveMcB]

If you're not sure how accurate the TPMS is maybe just compare readings against a decent pressure meter? I put an active set on my caravan - I'll admit it - set to 65psi cold on the meter. The TPMS showed exactly the same so I'm pretty confident it's accurate. What I found quite surprising is how much the pressures can go up, sometimes only 3 0r 4 but other times as much as 10psi after a fairly short time on the move. Ambient road temperature seems to be the biggest factor as it doesn't really do much braking.

 

[Jemster]

Lol, the lengths some people go to, to control tyres pressures within a single psi! I'm probably too far the other way, but I never check my tyre pressures. 30 psi, 32 psi, 35 psi, I defy anyone who reckons they can tell the difference. For road use, providing they are 30+, you'll be ok, unless you're some kind of serious track or drag strip enthusiast.

You may not be able to tell the difference, but your tyre can. My last car went through a set of rears (255/35/19) in under 5k miles because I had them over-inflated by about 0.3 bar. This resulted in the centre wearing away much faster than the edges. I was under 3mm across the middle 1/3rd of the tyre and over 5mm on the outer thirds. It made me paranoid about wear patterns (and alignment) as running through £400 of rubber in 4 months wasn’t a fun experience. I recheck every couple of weeks to be sure now.

Of course, thinner tyres on smaller wheels with lower power aren’t as much of an issue as wider low profiles are on a rwd car but the principles are the same. Luckily I have a garage within a mile of the house so could always check cold. Does the tpms system adjust its readings (internally) to compensate for temperature?

 

[D0C]

You may not be able to tell the difference, but your tyre can. My last car went through a set of rears (255/35/19) in under 5k miles because I had them over-inflated by about 0.3 bar. This resulted in the centre wearing away much faster than the edges. I was under 3mm across the middle 1/3rd of the tyre and over 5mm on the outer thirds. It made me paranoid about wear patterns (and alignment) as running through £400 of rubber in 4 months wasn’t a fun experience. I recheck every couple of weeks to be sure now.

Of course, thinner tyres on smaller wheels with lower power aren’t as much of an issue as wider low profiles are on a rwd car but the principles are the same. Luckily I have a garage within a mile of the house so could always check cold. Does the tpms system adjust its readings (internally) to compensate for temperature?

As I say, I'm too far the other way. Although having never put air in my tyres (I assume when it got serviced at 10k miles they put some in) my tyres are still doing ok at over 13k miles old!

 

[Terminator x]

The label inside the door is the "cold" pressure so should be set with cold tyres. I check mine perhaps once a month and normally they have moved by a few psi so I just pump them up a bit.

TX.

Sent from my STV100-4 using Tapatalk

 

[T-800]

So what you are saying is that the TPMS is making you paranoid?

Remember that the front brakes get a lot hotter than the rears, heating the wheels and tyres and that'll give you a spurious reading.

As has been said, nitrogen is just another way for some people to make easy money, as air is almost 80% nitrogen...

The other question is: what is more accurate? The TPMS sensors or the compressor with digital display? Maybe you should go "old school"...

View attachment 144577

No surprises the dealer doesn't know about the tyre pressure labelling in the car...

Is that a sonic screwdriver Oz ?

 

[T-800]

The label inside the door is the "cold" pressure so should be set with cold tyres. I check mine perhaps once a month and normally they have moved by a few psi so I just pump them up a bit.

TX.

Sent from my STV100-4 using Tapatalk

Agreed

I’m not one of these people who will say the label is wrong either, it’s there to guide you so why not take on board what it says, lot of development gone into tyre pressures I’m sure.....

Once a month is enough......

No point looking for a problem that doesn’t exist.......

Merry Xmas

 

[Ozmosis]

****** nitrogen people will be putting helium in next to shave a few kilos

Then it'll be time for "RS3 Squeaky Tyres" threads hahahahah!

 

[Ozmosis]

Is that a sonic screwdriver Oz ?

That or a gauged dog whistle...

 

[DW81]

Just seen you avatar mate lovely backdrop for this fabulous all weather vehicle

 

[Ozmosis]

Just seen you avatar mate lovely backdrop for this fabulous all weather vehicle

Yeah it's epic in the snow if you can find a big enough open space.

 

[Retroman]

Are these measurements at sea level and made during either high or low pressure weather conditions?

 

[D0C]

I remember as a kid (yes, a few years ago now) my dad having a slow puncture on his Rover SD1 that got progressively worse to the point that he'd make me go out there on an almost daily basis with the foot pump to put some air in it. As long as it had "about 15 psi" he was happy!

 

[DW81]

Hope he paid you mate

 

[D0C]

Hope he paid you mate

You must be kidding. He's tighter than a nuns chuff.

 

[DW81]

Doesn’t surprise me seeing that your Scottish I take it

 

[D0C]

Doesn’t surprise me seeing that your Scottish I take it

Absolutely not Scottish!

 

[AudiNutta]

Lol, the lengths some people go to, to control tyres pressures within a single psi! I'm probably too far the other way, but I never check my tyre pressures. 30 psi, 32 psi, 35 psi, I defy anyone who reckons they can tell the difference. For road use, providing they are 30+, you'll be ok, unless you're some kind of serious track or drag strip enthusiast.

I monitor them purely for controlling even tyre wear, my tyres always seem to wear unevenly regardless but it’s worth trying to keep on top of.

I will admit you struggle to feel a difference if any with the electrical assisted steering in these cars. The ride quality can change but very little because of Mag Ride. The biggest difference will be in an older power assisted steering car. If you’re inflating a tyre from sub-30psi, I think there is a difference to be had.

Nitrogen... don’t bother, I had this whole thing with my old GTR as what’s when’s ‘recommended’ in them... even the specialist I used to take it too used to laugh about it

I’ve heard good and bad things about it. I’m not necessarily looking for the performance benefits but more of reliable tyre pressures, supoosedly they don’t drop?

Just out of interest how reliable is the onboard tpms. You could be chasing your tail for nothing relying on computers and microprocessors to work out tyre pressure when a quick visual check would suffice, if it looks flat pump it back, simples.

Well tbh I think it’s pretty good! I put 39psi in the front and the TPMS shows bang on 39psi when lightly warm, increases slightly with lots of driving. I put 36psi in the rear, TPMS is telling me they are both 36.5psi under the same conditions.

You may not be able to tell the difference, but your tyre can. My last car went through a set of rears (255/35/19) in under 5k miles because I had them over-inflated by about 0.3 bar. This resulted in the centre wearing away much faster than the edges. I was under 3mm across the middle 1/3rd of the tyre and over 5mm on the outer thirds. It made me paranoid about wear patterns (and alignment) as running through £400 of rubber in 4 months wasn’t a fun experience. I recheck every couple of weeks to be sure now.

Of course, thinner tyres on smaller wheels with lower power aren’t as much of an issue as wider low profiles are on a rwd car but the principles are the same. Luckily I have a garage within a mile of the house so could always check cold. Does the tpms system adjust its readings (internally) to compensate for temperature?

As I replied to D0C above, I agree with you and this is the main reason I control tyre pressures to keep tyres wearing evenly.

 

[Phil3]

There’s a fraction under 80% nitrogen in normal air... in my opinion you need to be driving something very special such as an F1 car or such like to even notice the difference. For the sake of the tyre altering a fraction more/less psi during driving due to heat, I really don’t see the point in using just nitrogen... plus you have to pay for it... it’s just a waste... but that’s just my thinking

 

[Retroman]

The Michelin 12v inflator is supposed to be very accurate to +\- 1 psi. Worth checking pressures regularly on a high speed performance car. Enjoy the RS3 - wish I had one

 

[Spinstorm]

My TPMS is in bar not psi - I haven't checked how to change it yet.

Anyone want to share? is it as simple as a menu press?

 

[AudiNutta]

My TPMS is in bar not psi - I haven't checked how to change it yet.

Anyone want to share? is it as simple as a menu press?

Press the “Menu” button on the MMI to take you back as far as you can go. Either tab left or right using the buttons either side of the scrolling wheel and in settings there is an option for measurement units somewhere.

 

[teslaboy]

I run 2.7bar +/- 1 at the front and 2.3 +/-1 at the rear.
Always fill up when cold.

Incidentally the other week I had a kerbed front wheel fixed and the repairer only put 2bar in the tyre when refitting hence quite a large imbalance between front left and right (2 to 2.8 as read on the TPMS which was obviously reporting a tyre pressure issue) and I am 99% sure the steering wheel would pull to the right i.e the side with the lower pressure tyre. Pretty obvious really!

 

[Dodgygtr]

Tyre pressures can make a massive difference to the way the car handles but it’s also down to driver preference and feel. Also tyres make a difference to what pressure is needed. Most cars I’ve always put in 35 cold but on the GTR with cup2’s and runflats I put 29 hot pressure.

 

[royalsteve68]

There’s a fraction under 80% nitrogen in normal air... in my opinion you need to be driving something very special such as an F1 car or such like to even notice the difference. For the sake of the tyre altering a fraction more/less psi during driving due to heat, I really don’t see the point in using just nitrogen... plus you have to pay for it... it’s just a waste... but that’s just my thinking

you don't pay for nitrogen in Costco

 

[royalsteve68]

So what you are saying is that the TPMS is making you paranoid?

Remember that the front brakes get a lot hotter than the rears, heating the wheels and tyres and that'll give you a spurious reading.

As has been said, nitrogen is just another way for some people to make easy money, as air is almost 80% nitrogen...

The other question is: what is more accurate? The TPMS sensors or the compressor with digital display? Maybe you should go "old school"...

View attachment 144577

No surprises the dealer doesn't know about the tyre pressure labelling in the car...

i remember those well, had the exact same thing