On 15/08/2019 at 18:43, Rodge said:

 

The TPMS doesn't really care what the pressures are when you reset it. All it looks for is changes in tyre pressures relative to each other. And very roughly, every 10 °C change in temperature will change the tyre pressures by about 1 psi.

 

A quick google search says pressure variance is 0.19psi per degree Centigrade so very nearly 2psi per 10 degrees C.

Even with the 30+ deg C variance in a day that can (rarely) be experienced here I think I have only once been caught out and had to let a bit of pressure out over the course of the day.

TPMS uses the ABS system to compare wheel rotation to detect a loss of pressure.

On 17/08/2019 at 16:20, Gerrycan said:

TPMS uses the ABS system to compare wheel rotation to detect a loss of pressure.

And all 4 tyres should be at the same temperature unless you're pushing on when the fronts will be hotter.

^^^ That or as can happen, a binding brake causing a hot wheel and and expanding tyre with hotter air in it.

Just got back home from shopping in Burton -upon-Trent and the TPMS alerted me to low pressure front right tyre. Sure enough cross thread screw gone in between the thread blocks and will be surprised if it can be repaired. Have to wait until 10am on Sunday to find out if cheap repair or new tyre. Google search shows 215/55R18 tyres ranging from £56 (budget) to £136 for the Michelin Primacy it came with from the factory. At least it happened at 18,200 miles. I was going to rotate them this week before the first service in 2 weeks as service indicator showing 500 miles to service.

10 minutes ago, shyVRS245 said:

Sure enough cross thread screw gone in between the thread blocks and will be surprised if it can be repaired. 

Most tyre repairers will only repair if the screw is more than 25mm (1 inch) away from the sidewall.

1 minute ago, PetrolDave said:

Most tyre repairers will only repair if the screw is more than 25mm (1 inch) away from the sidewall.

It's right in the middle of the width so about 100mm from the edge.

43 minutes ago, shyVRS245 said:

It's right in the middle of the width so about 100mm from the edge.

 

Should be repairable.

On 17/08/2019 at 18:29, shyVRS245 said:

the middle of the width so about 100mm from the edge.

As @PetrolDave and @logiclee say.

Just now, KenONeill said:

As @PetrolDave and @logiclee say.

Thanks will confirm tomorrow.

I don't think I've ever had more than 12k from a set of front tyres so at 18k I'd be replacing them, lol

 

As for the OP, I'd suggest just getting a decent gauge yourself and a foot pump....

Edited 17 August, 20196 yr by Alex-W

7 hours ago, Alex-W said:

I don't think I've ever had more than 12k from a set of front tyres so at 18k I'd be replacing them, lol

 

As for the OP, I'd suggest just getting a decent gauge yourself and a foot pump....

Wife's previous car went back to the dealer in January 2018 with the original Bridgestone tyres it left the factory with and 28,600 miles on the clock rotated at 17,000 miles. They were still in decent nick but only had a 1.2TSi to cope with.

14 hours ago, shyVRS245 said:

Google search shows 215/55R18 tyres ranging from £56 (budget) to £136 for the Michelin Primacy it came with from the factory.

Those Primacy's do last, think I got 14-15k outta the originals on my little 1.4tsi however, they ain't the quietest of tyres. I changed them for Michelin Cross climates & I was very impressed with them, progress grip (until really cold), progressive slip when at the limits (no sudden break aways) & very much quieter than the Primacy's. Yeah I'd recommend them for normal use with the extra capabilities of an all weather tyre

Edited 18 August, 20196 yr by themanwithnoaim

16 hours ago, Gerrycan said:

A quick google search says pressure variance is 0.19psi per degree Centigrade so very nearly 2psi per 10 degrees C.

Even with the 30+ deg C variance in a day that can (rarely) be experienced here I think I have only once been caught out and had to let a bit of pressure out over the course of the day.

This is why I'm a Nitrogen user, I run 3bar all round on R19/235/35 Michelin PS4S, it's a slight compromise on comfort (however, I have DCC) but, the performance is excellent & I get pretty even wear if a little scrubbed on the edges. As my tyres don't really that last long, I've had NO false alarms from my TPMS

On 18/08/2019 at 09:07, themanwithnoaim said:

This is why I'm a Nitrogen user,

OK, I'll bite. How does filling a tyre with 100% Nitrogen rather than the more usual 80% exempt it from Gay-Lussac's law (also sometimes known as the pressure-temperature law).

40 minutes ago, KenONeill said:

OK, I'll bite. How does filling a tyre with 100% Nitrogen rather than the more usual 80% exempt it from Gay-Lussac's law (also sometimes known as the pressure-temperature law).

Dunno how but, what I do know is, it's the Costco way & when they're on offer nobody else's offers can match them on Michelin PS4S the current performance tyre.

On 18/08/2019 at 10:11, themanwithnoaim said:

Dunno how but, what I do know is, it's the Costco way & when they're on offer nobody else's offers can match them on Michelin PS4S the current performance tyre.

Hint - It doesn't. The reason race teams do is that they inflate tyres at ambient, but achieve running temperatures around 90C, at which point dry gas makes the actual pressure more predictable.

1 minute ago, KenONeill said:

Hint - It doesn't. The reason race teams do is that they inflate tyres at ambient, but achieve running temperatures around 90C, at which point dry gas makes the actual pressure more predictable.

Errrr inflate with what though, Air or Nitrogen ?

On 18/08/2019 at 10:25, themanwithnoaim said:

Errrr inflate with what though, Air or Nitrogen ?

That makes very little difference.

What matters is the moisture content of what gas(ses) are used to inflate the tyres.

 

The only real difference is that the Nitrogen comes out of cylinders and has effectively 0% moisture content, but air has an uncertain moisture content depending on the weather when the tyres are inflated.

Good news front tyre repairable and they are currently swapping the nearly new tyres from the back to the front and repaired tyre going on the back. Happy camper.

14 hours ago, Alex-W said:

As for the OP, I'd suggest just getting a decent gauge yourself and a foot pump....

If the car came without a spare wheel, there will probably be an air compressor incorporating a pressure gauge to be found under the boot floor. That is what I have, but I also got myself a separate gauge as it is a bit of a faff to deploy the compressor just to check pressures.

 

I am not a fan of foot pumps. When I have had them in the past, the pumping action has caused the nuts on the sides to come unscrewed, and by the time I noticed the nuts had got lost.

 

2 hours ago, shyVRS245 said:

Good news front tyre repairable and they are currently swapping the nearly new tyres from the back to the front and repaired tyre going on the back. Happy camper.

I am glad it went OK for you.

 

3 hours ago, themanwithnoaim said:

This is why I'm a Nitrogen user, I run 3bar all round on R19/235/35 Michelin PS4S, it's a slight compromise on comfort (however, I have DCC) but, the performance is excellent & I get pretty even wear if a little scrubbed on the edges. As my tyres don't really that last long, I've had NO false alarms from my TPMS

It would be a pointless expense me getting Nitrogen as I don't push any boundaries on public roads.

I have not had any false TPMS alarms either, but an unfortunate number of real specific puncture warnings (nails and screws) and one valid general warning from too long a pressure check period on somewhat old and increasingly porous Dunlop Sportmaxx.

The one time I had to let pressures down mid-journey was when I filled the tyres in near zero morning temps to my customary higher eco levels and then by mid-afternoon the temperature had risen to high 20's and the ride was just too uncomfortable (No TPMS involved).

 

1 hour ago, OldBoyScout said:

 I noticed the nuts had got lost.

 

Yes, I've heard that happens to some old boy scouts  

3 hours ago, shyVRS245 said:

Good news front tyre repairable and they are currently swapping the nearly new tyres from the back to the front and repaired tyre going on the back. Happy camper.

Total cost was £33 for the repair and front to back swap more than expected but didn't want to risk damaging the tyre/wheel when the garage is just 300metres from our house. Thanks for all the good advice yesterday saved me over £100 against a new Michelin.

5 hours ago, PetrolDave said:

What matters is the moisture content of what gas(ses) are used to inflate the tyres.

 

The only real difference is that the Nitrogen comes out of cylinders and has effectively 0% moisture content, but air has an uncertain moisture content depending on the weather when the tyres are inflated.

 1 atmosphere of air pressure will be in the tyre before the nitrogen is inserted. The tyre will thus be inflated with a mixture of pure dry nitrogen and air. Unless there is a clever method of air removal?