The 10/20% rule for tire pressure

[Remontoire]

Determining optimal tire presure by monitoring the cold and hot tire pressures.

Has anyone got anything to say about this rule? It's new to me, but sounds like it's been around a while.

I've started watching my own Metzeler Z6's and it's got my curiosity piqued.

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http://www.triumphrat.net/twins-tec...10-20-rule-for-tire-pressure.html#post1674652

"A technique for those wanting to get the most out of their tires on the street is to use the 10/20% rule.

First check the tire pressure when the tire is cold. Then take a ride on your favorite twisty piece of road. Then, measure the tire pressure immediately after stopping. If the pressure has risen less than 10% on the
front or 20% on the rear, the rider should remove air from the tire. So for example, starting at a front tire pressure of 32.5 psi should bring you up to 36 psi hot. Once you obtain this pressure increase for a given rider, bike, tire, road and road temperature combination, check the tire pressure again while cold and record it for future reference.

Each manufacturer is different. Each tire model is different. A tire design that runs cooler needs to run a lower pressure (2-3 psi front) to get up to optimum temperature. The rear tire runs hotter than the front tire, road and track. So the rear tire cold-to-hot increase is greater. Dropping air pressure has the additional side effect of scrubbing more rubber area."

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Ian

 

[NorCalBusa]

There's no such thing. Appropriate tire pressure depends on the tire, load, road surface, rider input and what outcome you desire. For some it may be high mileage, while others may want better traction or handling. Anything trying to do more than one of those is a compromise and not "optimum".

 

[Remontoire]

Can't seem to find any hard data

 

[Tom Mac 04a]

I just run the Mother's recommended pressure of 42 for both.. Got enough things going on in my head to worry about 1-2 lbs and saving a couple of miles worth of rubber.



But , if it works for you , then by all means go with it!

 

[Firstpeke]

The two things that most determine tyre pressure are weight and speed...... the size is primarily predetermined by the vehicle manufacturers choice of wheel size...

Don't forget that the air in the tyre is the PRIMARY suspension for the vehicle... too little = overloaded, too much = harsh ride and potential for impact damage

Pressures are not set to give tyre life, rather a compromise between comfort and handling.

The maximum safe pressure for a tyre is marked on the sidewall.

Minor variations for road use can be determined by wear pattern and/or handling..... there are compromises to be made.

Too hard and your dentist will be kept busy as well as scaring you silly in the wet.. too soft, handling goes again and wear rate will increase.

We used to reckon on Michelin heavy truck tyres that an under inflation level of just 10% could increase wear by more than 25%..... much the same applies to other tyre sizes too....

Over inflation is damaging from an impact damage point of view, under inflation is damaging from an excessive and adverse wear point of view.

As I said, it's about compromise for the end user... setting pressures that will give "acceptable" wear rates with similarly acceptable handling and comfort...

I tend to run recommended rear pressures and around +5% on the front for the bike, and laden pressures on the front and unladen pressures on the rear for my front wheel drive car.

That is for MY bike and car, not necessarily yours.....

In any case, you should never exceed the pressure shown on the sidewall of the tyre.

YEMV.