The sidewall of my Subaru’s right front tire says “Inflate to 45 psi max”. The tire shop mechanic says I should go by the Subaru label on the door pillar, which says tires should be inflated to 34 psi. I think he’s full of it – the tire manufacture knows better than the car manufacturer what pressur…

[image] MikeInNH: Tire pressure is based on the tire’s optimal footprint and the weight of the vehicle. It’s really simple physics. It isn’t that simple. A tire is not a balloon. @CapriRacer can weigh in on this but there isn’t a direct relationship between contact patch and tire pressure. Th…

[image] MikeInNH: Tire pressure is based on the tire’s optimal footprint and the weight of the vehicle. It’s really simple physics. You can actually determine the weight of a vehicle by the footprint and the tire pressure. Tired Weight: Math & Mechanics Science Activity | Exploratorium Teacher…

You’ll always find examples that aren’t in the norm. Sure run flats have issues. But the formula works. I’ve done it in the lab of my physics class years ago. The tire tread will have a bearing on the calculation, but that’s solvable. Remove run-flats from the equation and the sidewalls really don’t…

[image] MikeInNH: But it DOES WORK How do you know it works? Or how accurate it is? Neither post actually scaled the vehicles to confirm the relative accuracy of the method. What was your experience with the accuracy? The only posts I can find Googling the method are from educational institu…

[image] Mustangman: How do you know it works? Or how accurate it is? Read my previous post. I’ve actually done the experiment in my college physics class. You can do a google search. That experiment is being performed by many colleges all over. My daughter did the experiment at her undergrad …

[image] MikeInNH: Read my previous post. I’ve actually done the experiment in my college physics class. You can do a google search. That experiment is being performed by many colleges all over. My daughter did the experiment at her undergrad physics class at MIT. Some states still use this metho…

I saw it. And I agree is doesn’t work in THOSE cases. I also posted examples of where it works fine (with a margin or error). This is known physics. It can be applied to cars and trucks. If the science isn’t valid then there are probably thousands of tickets given out to truckers because some state …

You keep posting links where there isn’t any data - only a statement that it works. I’ve given you 4 examples with data where it does not and I expect from you a link to 4 different examples - with data - where it does. Not made up data, links to some people who have actually confirmed it works.

An older friend was very badly injured by an exploding tire during WWII. He was assigned to work on an aircraft carrier, repairing & re-inflating the airplane tires, which would often be damaged during hard landings. One of the airplane tires exploded during the inflation process.

[image] CapriRacer: I’ve given you 4 examples with data where it does not and I expect from you a link to 4 different examples - with data - where it doe weigh your car - YouTube This isn’t something people do every day. But let me inform all the Physicists, college professors and Mechanical…

Tire pressure -- who to believe?

Maintenance/Repairs

CapriRacer June 16, 2023, 5:55pm 35

I’m sorry, but perhaps you missed the webpage I posted that gave 4 examples where the math doesn’t work - particularly the quote “It is well-known, to tire engineers, that the average footprint pressure produced by a tire can be above or below the inflation pressure, depending on tire load.”.

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Tire pressure -- who to believe?

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