Tyre bods your knowledge please...

[Tom@JMS]

Right looking from some info from anyone who may know a thing or two about tyres: running temps, pressures etc: ideally when used on track

I would like to know the following:

1. Can you accurately gauge external tyre surface temperature from the air temp inside the tyre?

2. What sort of temperature range does the air inside the tyre move through (cold to general overheating)

3. What sort of temperature range does the surface of the tyre move through (again from ambient to overheating.)

4. With all/any the above how does the pressure increase relate to temperature increase?

Does anyone know a source of info/graphs/calcs based on any of the questions above?

Thanks all.

T

 

[fUbAr]

Ryan K is your man, he runs NWPerformance in the traders section who specialise in tyres...

 

[Tom@JMS]

general tyre fitting etc, or more in depth?

 

[White16valver]

Those sort of Qs are pretty much racing level info!

 

[Tom@JMS]

Possibly, but there are people floating around on here with that level of experience

 

[geesus69]

there was an article in track and race car a while back where they were testing a tyre pressure system and linking it in with temps

interesting read although maybe still not in depth enough to answer all your Q's

 

[Tom@JMS]

ok mate thanks for your help, any idea what issue number the mag was?

 

[geesus69]

i'll dig it out tonight

 

[JamesS]

1. Can you accurately gauge external tyre surface temperature from the air temp inside the tyre?

No. Explanation below.

2. What sort of temperature range does the air inside the tyre move through (cold to general overheating)

This is hugely dependant on the car and what it is doing. High speeds do not create significant heat inside the tyre chamber; this is done from braking and heat soak from the brakes into the rim, which in turn heats the air in the cavity. Chances are that you'll actually see the highest air temp after you have finished on track and leave the car to stand for a couple of mins because there is no air passing around the wheels to cool it, and the brakes heat soak into the wheels.

At Snetterton I saw my FL tyre chamber temperature go from ambient 25°C to 80-85°C in 15 (ish) mins, from where it stabilised (mainly due to the tyre starting to lose grip and me not being able to push harder), but after entering the garage the temp went up to 95°C, before cooling.

Performance cars can easily see over 100°C in the tyre chamber, and if you take some extreme cars, 140°C+!

3. What sort of temperature range does the surface of the tyre move through (again from ambient to overheating.)

Hugely dependant on tyre type, so there is no clear answer. Tyre temp is best measured in the carcass and not directly on the outside as this can be easily influenced by external factors.

On my everyday run to work (20 mins on back roads), with an ambient air temp of 20°C, my carcass temperatures (Yokohama Parada Spec 2) will be something like 45°C on the front, and 40°C on the rear.

Haven't had a chance to run on the track this year, so don't have any data for track temps.

4. With all/any the above how does the pressure increase relate to temperature increase?

If you fill your tyre with standard 'air' (not dried, or pure nitrogen, cfc's etc), then the pressure will follow the ideal gas law (quick search on the internet will give you everything you need to know about this, but remember to use °K and not °C for any calculations).

 

[Tom@JMS]

Great stuff

What are you using to gather the temp data out of interest?

 

[JamesS]

What are you using to gather the temp data out of interest?

InfraRed temperature sensors mounted in each wheel, which measure the tyre carcass temperature from the inside and transmit the data wirelessly back to receivers on the car.

The Cup serves well as a test car for new technology! :approve: