Tyre pressure on door post

[FiestaRed]

Can anyone tell me what the two sets of figures are shown on the tyre pressure sticker on the door pillar please?

[Bernard Foy]

15 minutes ago, FiestaRed said:

Can anyone tell me what the two sets of figures are shown on the tyre pressure sticker on the door pillar please?

One is for when the car is unladen and obviously the higher pressure is for when the car is fully loaded.

[TonyHSD]

On some cars the two different pressures sets are in connection to vehicle speeds, up to 100mph and above 100mph. General rule is that the faster you go the higher the pressures in the tyres should be., this also matches the car loads, fully loaded equals extra pressure. 👍

[FiestaRed]

11 minutes ago, TonyHSD said:

On some cars the two different pressures sets are in connection to vehicle speeds, up to 100mph and above 100mph. General rule is that the faster you go the higher the pressures in the tyres should be., this also matches the car loads, fully loaded equals extra pressure. 👍

Thanks for the help. The two sets of pressures shown on the sticker does seem to refer to speeds above and below 160km.

[Roy124]

Basically you can ignore the high settings. In 15 years I only managed 100 mph for a sustained period of about 20 minutes in Mercedes E Class. 

[TonyHSD]

10 minutes ago, Roy124 said:

Basically you can ignore the high settings. In 15 years I only managed 100 mph for a sustained period of about 20 minutes in Mercedes E Class. 

Agreed, and Toyota cars are the last cars that you want to drive at 100mph or above, they are simply not good at that. 👍

[Roy124]

My garage, father and son, often go to Stuttgart each in a separate Merc.  

One day, dad in the rear gets overtaken by an S600 doing about 140 with nobody in it. 

Calls son, says lookout.  Moments later S600 cruises passed.  Tiny figure visible behind the wheel and barely taller than the dash. 

When someone has a 40 mph overtake you know about it.  When you're doing 100 that's something else. 

[JARC1]

1 hour ago, Bernard Foy said:

One is for when the car is unladen and obviously the higher pressure is for when the car is fully loaded.

Not strictly true, if you read Toyota Manuals. They state it is dependent on speed. I would not be inclined to use my Avensis at 100 mph.

Regards and Best Wishes, John

[Rhymes with Paris]

I always try to stay below 100mph when it's wet or icy.🛣️

[Stivino]

2 hours ago, JARC1 said:

I would not be inclined to use my Avensis at 100 mph.

Mine will do that all day long.  But, I would never do that.

[paul9]

My Avensis seemed to have a 120mph limit set by Toyota. Allegedly.😙

[Cyker]

I tend to use the higher pressures as they often give better mpg, but I always found it weird they spec higher pressures for higher speeds rather than load - The faster you're going the hotter the tyres will get, so they will naturally raise their own pressure anyway; Starting with a higher pressure would just make that difference worse I would think!!

Then again maybe having more pressure will reduce flex which will stop the tyres heating up as quickly??

[TonyHSD]

32 minutes ago, Cyker said:

I tend to use the higher pressures as they often give better mpg, but I always found it weird they spec higher pressures for higher speeds rather than load - The faster you're going the hotter the tyres will get, so they will naturally raise their own pressure anyway; Starting with a higher pressure would just make that difference worse I would think!!

Then again maybe having more pressure will reduce flex which will stop the tyres heating up as quickly??

Correct.
Higher the speed higher the pressure should be.  
When the wheels spins at very high rpm the tyres change their shape as a result of extreme centrifugal forces and they can even stretch and pop out of the wheels and loose all air, explode. Another issue as you said softer tyres heat up more and when they are very low on pressure the critical number is below 1 bar they heat up to very high temperature and explode again, the tyre walls can’t handle it. Always when we have extreme hot and extreme cold weather I see plenty of these broken down cars with disintegrated tyres . Two nights ago a Nissan micra front of me on M1, again same signs smell of burning rubber, then pop sound and then the micra pulled over to the hard shoulder, thankfully there was one there. Front right tyre was burst open. 

[Roy124]

The Mercedes required significantly higher pressures for both load and speed. 

[TonyHSD]

Here , you can skip to 12:00 to see the results. The lower the pressure the higher the risk of tyre expansion and blow up. 

 

[FiestaRed]

Thanks for all the help, really appreciated.