Tire pressure for over 100 mph
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Member
Joined: Nov 2015
Posts: 143
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From: Raleigh, NC
2006 E55 AMG
Tire pressure for over 100 mph
The gas cap cover gives two different tire pressures: one below 100 mph and one over 100 mph. If I only go over 100 mph a few times per week, and even then only for short periods, is it okay to keep the lower tire pressure, or should I bump it up to the 100 mph number? Is anyone doing daily city driving on the higher number, and, if so, how's the ride?
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Joined: May 2015
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From: Miami, FL
2003 CL 600
The higher pressure it to maintain the load rating at higher steady speeds. Unless you are running the car fully loaded, as in 4 people + luggage, and maintaining highway speeds, you won't have any issues.
For me personally I like to run a few psi higher than the normal settings but on a car with a low and high number, somewhere in the middle usually gives a nice balance of handling and ride.
For me personally I like to run a few psi higher than the normal settings but on a car with a low and high number, somewhere in the middle usually gives a nice balance of handling and ride.
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Joined: Oct 2009
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Seat Alhambra
At higher speed the wheel makes more cicles a second and so produces more heat a second, Cooling down is dependent on temperature difference between inside tire temp and outside tire temp , and between temp of hottest part of rubber and tire inside temp.
so if you drive above 100m/160km/h for even a minute , some spots of rubber get to hot and harden, and crack in next bendings, and so damage to tire is done.
If once damaged the tire can blow after a while because every bending/deflection of the tire damages the hardened parts a bit more.
So my answer is , that even if you drive 100m/h for even a minute once a while, you need the pressure adviced for above 100m/h.
but the advice is often given for Fully loaded car, so Axles loaded to the GAWR's ( gross Axle Weight Ratings), and in your use you mostly have lower load, with for instance only driver and a little load.
This would mean that your advice for below 100m/h is probably enaugh for the lower loads above 100m/h.
I am able to calculate the needed pressures , if you provide me with loads on seperate tires ( hard to determine) and tire data.
Greatings from a Dutch, Pigheaded Selfdeclared tirepressure-specialist.
so if you drive above 100m/160km/h for even a minute , some spots of rubber get to hot and harden, and crack in next bendings, and so damage to tire is done.
If once damaged the tire can blow after a while because every bending/deflection of the tire damages the hardened parts a bit more.
So my answer is , that even if you drive 100m/h for even a minute once a while, you need the pressure adviced for above 100m/h.
but the advice is often given for Fully loaded car, so Axles loaded to the GAWR's ( gross Axle Weight Ratings), and in your use you mostly have lower load, with for instance only driver and a little load.
This would mean that your advice for below 100m/h is probably enaugh for the lower loads above 100m/h.
I am able to calculate the needed pressures , if you provide me with loads on seperate tires ( hard to determine) and tire data.
Greatings from a Dutch, Pigheaded Selfdeclared tirepressure-specialist.
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Joined: Oct 2009
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Seat Alhambra
If you want comfort , gripp, and savety , you can use the pressure up to 100m/h, and probably ride that over 100m/h once a while, when you are alone in car and a little load.
Then when you have incidental higher load , you must realise that you must not drive that fast.
So for every speed and load on tires , I can calculate a pressure range.
So a highest pressure with still acceptable comfort and gripp, and a lowest pressure for the speed you wont go over for even a minute, at wich no damage to tire.
That speed thing also works the other way , so lower speed , more deflection allowed, so lower pressure for the same load , or higher loadcapacity for the same load.
So one pressure can be yust fine for your normal use, but for lower speed it can be fine for fully loaded .
Roughly you can add 1 Loaindex-step for every 10km/6,5m lower speed then 160km/100m/h, and the other way around 10km higher speed is 1 LI-step lower maximum load.
The maximum load of a tire is calculated for the reference-pressure ( Standard load P-tire 35 psi) and reference speed of 160km/99m/h, this up to V-speedrated tires.
Will give a picture I made of the official system used , once got hold of the European formula with the extra's for speed and camber-angle.
My idea is to replace that official system, wich is for every speedrating different, by my simpler system of adding or substacting the loadindex for speed.
Then when you have incidental higher load , you must realise that you must not drive that fast.
So for every speed and load on tires , I can calculate a pressure range.
So a highest pressure with still acceptable comfort and gripp, and a lowest pressure for the speed you wont go over for even a minute, at wich no damage to tire.
That speed thing also works the other way , so lower speed , more deflection allowed, so lower pressure for the same load , or higher loadcapacity for the same load.
So one pressure can be yust fine for your normal use, but for lower speed it can be fine for fully loaded .
Roughly you can add 1 Loaindex-step for every 10km/6,5m lower speed then 160km/100m/h, and the other way around 10km higher speed is 1 LI-step lower maximum load.
The maximum load of a tire is calculated for the reference-pressure ( Standard load P-tire 35 psi) and reference speed of 160km/99m/h, this up to V-speedrated tires.
Will give a picture I made of the official system used , once got hold of the European formula with the extra's for speed and camber-angle.
My idea is to replace that official system, wich is for every speedrating different, by my simpler system of adding or substacting the loadindex for speed.
Thread Starter
Member
Joined: Nov 2015
Posts: 143
Likes: 7
From: Raleigh, NC
2006 E55 AMG
Wow, I'm impressed by the work you've put into this. Still, you make me believe I need to add a few PSI above 35 for my V rated tires because of my rare jaunts into the triple digits.
