How hot is too hot for normal car tyres (Michelin PS4)?
Discussion
Hello people,
I have a KIA EV6, very cool car riding on 4 Michelin PS4 SUV (MO) tyres - 255/45 R20.
Kia suggest a tyre pressure of 36PSI but in this hot weather I notice that over long motorway drives they reach 40psi, which is fine I'll under inflate them a little for a hot pressure of 38psi (?).
What does worry me a little is that the sensors show 40c 'tyre temperature' (I guess that's the air inside the tyre? TPMS system sensor). Should I be worried about this? I think I saw the max PSI allowed by Michelin is 50 so I have some headroom there, but what are max temperatures for a tyre like this? Planning a log road trip in Europe so can easily do 500 miles per day at highway speeds in this hot weather.
Advice is appreciated, thank you!
I have a KIA EV6, very cool car riding on 4 Michelin PS4 SUV (MO) tyres - 255/45 R20.
Kia suggest a tyre pressure of 36PSI but in this hot weather I notice that over long motorway drives they reach 40psi, which is fine I'll under inflate them a little for a hot pressure of 38psi (?).
What does worry me a little is that the sensors show 40c 'tyre temperature' (I guess that's the air inside the tyre? TPMS system sensor). Should I be worried about this? I think I saw the max PSI allowed by Michelin is 50 so I have some headroom there, but what are max temperatures for a tyre like this? Planning a log road trip in Europe so can easily do 500 miles per day at highway speeds in this hot weather.
Advice is appreciated, thank you!
I wouldn't worry about trying to second guess what is happening on a hotter than usual day. The book temps should be set "cold", say first thing in the morning. As the car is driven, the temps rise as a result of the continuous deflections of the tyre as it rotates. The faster it rotates, the higher the temperature rise and so the bigger the pressure increase. This is all calculated in to support the tyre better at those higher speeds.
Reduce the running pressures and the tyre can overheat and eventually fail. Following the manufacturer's recommendations is very wise in this case.
Reduce the running pressures and the tyre can overheat and eventually fail. Following the manufacturer's recommendations is very wise in this case.
Edited by neenoy on Monday 18th July 16:36
My jeep tyres are set to 34 cold, and they always get to 37 or 38 when in use even in winter, and today 40 on the motorway. That's how tyres work as far as I know - movement = deformation = heat = pressure increase.
By far the safest thing to do is set them as the manufacturer lists on the tyre pressure table stuck somewhere on your car that shows the correct pressue for the tyre size , speed and vehicle loading you will be doing, rather than making guesses and setting them lower than they should be - they know more than you do and they don't just pluck those numbers out of (ahem) thin air.
By far the safest thing to do is set them as the manufacturer lists on the tyre pressure table stuck somewhere on your car that shows the correct pressue for the tyre size , speed and vehicle loading you will be doing, rather than making guesses and setting them lower than they should be - they know more than you do and they don't just pluck those numbers out of (ahem) thin air.
Mammasaid said:
F1 tyres run at 100-110C, so I think road tyres will cope with 40C.
Michelin Pilot Sport Cup 2 R tyre has an ideal operating temp of 90ºCUHP road tyres are happier (in the dry) at 80ºC - but that's tyre temp, not ambient air temp
But trying to find this info for a particular tyre is not easy...and most people wouldn't know what to do with it anyway, especially if their car doesn't have a tyre temp gauge (for the air inside or the rubber itself).
neenoy said:
I wouldn't worry about trying to second guess what is happening on a hotter than usual day. The book temps should be set "cold", say first thing in the morning. As the car is driven, the temps rise as a result of the continuous deflections of the tyre as it rotates. The faster it rotates, the higher the temperature rise and so the bigger the pressure increase. This is all calculated in to support the tyre better at those higher speeds.
Reduce the running pressures and the tyre can overheat and eventually fail. Following the manufacturer's recommendations is very wise in this case.
This. Just keep the tyre pressures for the recommended load. This is not exceptionally hot weather for tyres.Reduce the running pressures and the tyre can overheat and eventually fail. Following the manufacturer's recommendations is very wise in this case.
Edited by neenoy on Monday 18th July 16:36
I lived in the Dhahran area of Saudi in the 1990s. I drove a variety of vehicles, and in temperatures ranging from under 10c to over 50c. We never gave the tyre pressures and temperatures a second thought, and they didn’t need it. I drove my Laguna flat out almost everywhere every day, and went at 150mph a few times in other cars, at all times of year. Petrol at 2p per litre helped 
If you want to be safer than safe, maybe reduce your speeds a little, that’ll more than compensate.
If you want to be safer than safe, maybe reduce your speeds a little, that’ll more than compensate.
Manufacturers recommend tyre pressures for cold (or ambient temperature) knowing that in use the try will get hotter.
It’s about presenting a flat tread surface to the road. On race cars temp is taken before racing and directly after across the tread width, a temp difference across the tread guides both how flat the tread is to the track and the suspension settings, you then compare that to the temps between all tyres the idea is to get them all even after a race and adjust the start pressures to give even temps after the race.
Car manufacturers recommend tyre pressures for low passenger occupancy and a higher pressure for full occupancy with luggage and also sustained high speed, the tolerance is so wide and not that specific that adjusting your pressure because the temp is a few degrees higher is a random stab in the dark.
It’s about presenting a flat tread surface to the road. On race cars temp is taken before racing and directly after across the tread width, a temp difference across the tread guides both how flat the tread is to the track and the suspension settings, you then compare that to the temps between all tyres the idea is to get them all even after a race and adjust the start pressures to give even temps after the race.
Car manufacturers recommend tyre pressures for low passenger occupancy and a higher pressure for full occupancy with luggage and also sustained high speed, the tolerance is so wide and not that specific that adjusting your pressure because the temp is a few degrees higher is a random stab in the dark.
TB404 said:
Hello people,
I have a KIA EV6, very cool car riding on 4 Michelin PS4 SUV (MO) tyres - 255/45 R20.
Kia suggest a tyre pressure of 36PSI but in this hot weather I notice that over long motorway drives they reach 40psi, which is fine I'll under inflate them a little for a hot pressure of 38psi (?).
What does worry me a little is that the sensors show 40c 'tyre temperature' (I guess that's the air inside the tyre? TPMS system sensor). Should I be worried about this? I think I saw the max PSI allowed by Michelin is 50 so I have some headroom there, but what are max temperatures for a tyre like this? Planning a log road trip in Europe so can easily do 500 miles per day at highway speeds in this hot weather.
Advice is appreciated, thank you!
You should always inflate tyres to their correct pressures when cold (before they have been driven on).I have a KIA EV6, very cool car riding on 4 Michelin PS4 SUV (MO) tyres - 255/45 R20.
Kia suggest a tyre pressure of 36PSI but in this hot weather I notice that over long motorway drives they reach 40psi, which is fine I'll under inflate them a little for a hot pressure of 38psi (?).
What does worry me a little is that the sensors show 40c 'tyre temperature' (I guess that's the air inside the tyre? TPMS system sensor). Should I be worried about this? I think I saw the max PSI allowed by Michelin is 50 so I have some headroom there, but what are max temperatures for a tyre like this? Planning a log road trip in Europe so can easily do 500 miles per day at highway speeds in this hot weather.
Advice is appreciated, thank you!
The pressure will increase as they have been driven on, as others have said, but you shouldn't reduce the warm pressure as the tyre won't be at the correct psi when it cools again.
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