What time do you check you tyres on a sunny day

[olddriver]

I checked my tyres at 8 am today, started on the shady side, then did the sunny side and effectively they were 2psi higher, so I left it to check tonight.

Any advice please?

[Bper]

Hi,you did the right thing by checking your tyre pressures and noticing the difference between the sunny and shady sides. Car tyres absorb heat from the sun, which heats the air inside them.

As the air gets hotter, the molecules move faster and spread out more, increasing the pressure inside the tyre.The 2 psi difference you measured is a normal increase due to the temperature difference.Don't adjust the pressure tonight, since you checked the sunny side after it had been heated, adjusting the pressure now would make them underinflated when they cool down.Check the pressure again in the morning It's best to check tyre pressure when they are cold, after been sitting for a few hours. Look in your owners manual or sticker on the driver's door jamb for the recommended tyre pressure. Inflate all four tyres to the same pressure when they are cold.Hope this helps

[mpm235]

Spot on advice from Bper

[Roy124]

17 minutes ago, olddriver said:

Any advice please?

Start on the sunny side? 😂

Seriously your question is quite interesting.   Suppose you set your tyre pressures to the correct value on a winter's day you should see a reading of +2 or 3 psi after even a short run.

Now assuming no change between then and the hot weather we are now experiencing those tyres, correctly inflated before, will now read 2 psi higher before you drive and will be up to 5 psi over the recommended value after a drive. 

The converse is true and it would be best to adjust pressures every week when they are cold.

 In your case, indeed check in the evening once the heat of the sun is gone and the tyres have cooled after use.

[Roy124]

@Bper said "Inflate all four tyres to the same pressure when they are cold."

Only if that is the recommendation.   My Corolla MY17 and Yaris Cross MY21 both have a pressure 2psi lower for the rear.

Also check the pressures after the specialists have had the hands on your car.  My Toyota dealer handed over the car with 42psi delivery pressures, KwikFit and National Tyre both set 36psi rather than 29psi.

 

 

[Haliotis]

Throughout the seasons, and with daily weather changes, the temperature of a car’s tyres will change in accordance with the ambient temperature, whether the car has been standing in the sun or shade, and will heat up whilst being driven.

I always inflate/check my tyre pressures when the car has been standing out of the sun, and long enough for them to be at ambient temperature.   For this reason I never check my tyres at a fuel station because they would be warm from being driven, and any obtained readings would not be accurate.

[olddriver]

1 hour ago, Roy124 said:

Also check the pressures after the specialists have had the hands on your car.  My Toyota dealer handed over the car with 42psi delivery pressures, KwikFit and National Tyre both set 36psi rather than 29psi.

 

 

Also check the torque on the wheel nuts, I am fairly sure I read, maybe in my handbook, that you shouldn’t trust the guns that they use, always use a torque wrench, my GR86 is 89 ft-lbf, the highest I have ever applied other than on an old Minx axle nut which I think was 150 ft-lbf, had to borrow a wrench from work for that!

[Roy124]

25 minutes ago, olddriver said:

Also check the torque on the wheel nuts, I am fairly sure I read, maybe in my handbook, that you shouldn’t trust the guns that they use, always use a torque wrench, my GR86 is 89 ft-lbf, the highest I have ever applied other than on an old Minx axle nut which I think was 150 ft-lbf, had to borrow a wrench from work for that!

Spot on, 120nm.  

I checked mine after the last wheel change and they were OK.

[Haliotis]

56 minutes ago, olddriver said:

Also check the torque on the wheel nuts, I am fairly sure I read, maybe in my handbook, that you shouldn’t trust the guns that they use, always use a torque wrench, my GR86 is 89 ft-lbf, the highest I have ever applied other than on an old Minx axle nut which I think was 150 ft-lbf, had to borrow a wrench from work for that!

The pneumatic impact wrenches that garages use on wheel studs should only be used for removal of the studs.  For refitting and tightening, only a torque wrench should be used, and this needs to be used correctly.

At a Kwik-Fit depot I once stopped the tyre fitter as he was doing things wrongly - (a) their wall chart torque for my car was wrong, and (b) he was using the wrench incorrectly.  The manager came over and an altercation began.  To stop that, I said that I was a development engineer and that part of my duties was to train operatives in the use of torque wrenches (this was all true), and I took my own Norbar wrench (actually the same as the Kwik-Fit one) from the boot and showed how it should be done.  One of the fitter’s faults was that he was giving the wrench an extra push after it had “clicked”.   The manager was a bit rueful, and the fitter, although he kept quiet, looked about ready to explode.

One other thing - when I have used the wrench, I always turn it back to Zero load. This relieves the spring from being under constant compression.

[ToyotaFanDriver]

I'm up very early so in summer about 5 or 5.30am for me. Its light outside and the sun as not had time to shine on the car since its quite low down.

[Trewithy]

I check my tyres first thing in the morning once a month.  luckily my drive is in the shade until about mid morning.  I haven't had to add air to any of my tyres for a couple of months now as the increasing ambient temperature more than compensates for any natural air loss.  

When you have new tyres and valves fitted it is always worth checking that the air valve innards are fully screwed in as this is a potential place for an air leak.  You can get an inexpensive tool for this in Halfords.

[Roy124]

I didn't watch tge NT fitter but I think he used one of those 6 arm jobbies you can get a real spin on them 🤔 

[Cyker]

I must say having the live pressure sensor view has totally changed how I look after my tyres - I used to check the pressures every 2-4 weeks, having to factor in the temperature differential as mentioned above, but now don't bother at all and just keep an eye on them in the car! If one is a bit low I just add however many psi it's off by when I get a chance, and don't even wait for it to get cold like I used to have to  

It's quite interesting seeing how much the pressures change though - Even just driving normally it'll quickly rise by a couple PSI, and at higher speeds it'll go higher still; I've seen it get up to 42-ish psi just from driving on the motorway in summer!