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Tire pressure behavior between tires on car

I was wondering if tire pressure tends to lose faster on the front tires than rear and if they tend to sag more for tires that do sag (radial ply? or maybe bias ply).

I noticed it seemed that way on the cars I drove, unless that actually indicates some problem with the car suspension, etc. Though I assume it’s plausible that they lose air faster as there is more weight at the front with the engine and all?

I too have noticed that rear tires seldom seem to lose air compared with front tires. Of course with a damaged tire or rim, all bets are off.

Maybe it’s because front tires take much more of a beating–they take the lateral load of the car when cornering and flex somewhat as well. Most cars being front wheel drive, they also twist somewhat when delivering torque to the pavement to move the car. Front wheels do the majority of the car’s braking too, and typically the highest weight will be on the front wheels, as the engine and other heavy stuff is right there. Rear wheels just need to follow along most of the time.

A theory.

The front tires are subjected to more cornering force than the rears. That means they are pulled away from the rim with a higher force - and even though they don’t actually become dislodged (unseat), that force will open small holes and allow some air to escape.

In addition to what CapriRacer said I think the flexing also makes more air diffuse right through the rubber itself.
I have a couple of bicycles that get rarely ridden (a tandem and my wife’s bike) and they lose air more slowly than the bike I ride to work every day.
When my bike was stolen and I rode my wife’s bike to work it started losing air at a higher rate.
Since bike tires have inner tubes there is no loss where the tire meets the rim; air goes right through the rubber.

When I had my 72 Beetle (engine in rear), the rear tires lost air and wore out more quickly. Since then all my cars have had front engines and the front tires lose air and wear out more quickly.

It seems natural to me that the tires that carry the most weight will have the most symptoms.

A lot of factors affect pressure including weight, cornering and speed. Theoretically, you should carry more pressure on the tires carrying the greater weight. Unfortunately we don’t drive HUMVEEs that can alter pressure “on the go”…or fortunately, which ever way you want to look at it.