Tyre pressures.?

Question

Why oh why do people keep saying that the correct tyre pressure for a car is the figure on the tyre itself. One guy actually said he was a car mechanic and said it!!

To the people saying it, STOP, STOP, STOP, you will kill someone.

Answer 1

Well, I actually read what you wrote, others clearly didn't!  You're quite right, and it's a point I make every time.  The quoting of the figure on the sidewall is an American requirement and for some obscure reason many seem to misunderstand what it is.

Answer 2

The pressure on the tyre is the maximum operating pressure of the tyre. Don't put that much pressure in the car tyre. Use the pressure the manufacturer recommends. If your not sure it is usually between 28-32 psi.

Answer 3

Most cars these days have stickers somewhere in the driver's door shut-line with tyre pressures on.  There should be pressures for normal vehicle use and also for when the car is heavily laden.  Pressures should be taken when the tyres are cold, and checked regularly.  As far as I'm aware there are no numbers on the tyre sidewall that relate to pressures, these numbers are just the tyre dimensions and speed ratings.

Answer 4

The tire pressure on the sidewall is the max that can be used for loads but you should always following what the manufacturer recommends either in the manual or on the door jam.

Answer 5

You will find details in:-

1) Owner's manual &

2) Driver side door jamb (below the lock) &/or

3) Fuel filler cap

Do not listen to other people.

Answer 6

last time I looked, those numbers on the tyres were specs of the tyres themselves pertaining to width, radius and rim allotment.

the tyre pressure guide is on the the drivers side door towards the bottom. again this is just a guide. they give you a range anyway. after a while, you'll get a feel for the correct pressure of your tyres. too much feels too rugged and too little feels sluggish.

the correct tyre pressure will result in a better ride, better tyre life, better suspension life and better fuel economy.

I don't believe your vehicle load affects your tyre pressure that much unless you're planning to add on a couple of tonnes worth.

I advise you get yourself a tyre guage. they're fairly cheap and easy to use. it beats relying on the automatic ones in petrol stations. you never know when those are faulty.

additional note. over inflation will cause the tires to wear out from the middle and under inflation will cause the edges to wear out first. and vice versa. if you see your tires wearing out in the middle, it means you're over inflating your tyres and so on. over inflating your tyres is dangerous since air expands when it's heated and the air in your tyres heat up when they start rolling.

also, in wet conditions or when you have to drive over loose rock, gravel or dirt roads, it helps to under inflate your tyres a bit to give you a little bit more traction.

Answer 7

Bardic is right. Also remeber that pressures may need to be varied depending on the load in the vehicle, so find out and get it right.