Are The Professionals Correct?

[Metal Head]

Hi,

I went on a basic car course to improve ones skills. Prior to arriving for the course they wanted your car tyres to have a PSI reading (pounds per square inch) of at least 36 irrespective of the size of your car (including 4WD):oo: This is a 20% higher than the recommended pressure as advised in the car handbook that came with the vehicle. They (the course advisors) said that the car would handle better and the tyres would last longer!!. However, I would think those who who gave the recommendation in the handbook would know best:?

Who's advice do you think I should listen to?

Cheers
MH

[DavidG]

The handbook is a compromise between ride and handling.
Increasing tire pressure keeps the tread pattern in shape better, increasing grip. Lower pressures allow the tread to roll together.

Or so I was told...... :dunno:

[rrich]

Actually both are wrong when it comes to tire wear.

The manufacturer recommends tire pressures consistent with the maximum load in the vehicle. This is to make the manufacturer litigation proof.

The logic behind the "Experts" suggestion is beyond my understanding.

Altering the tire pressures can change the handling characteristics of the vehicle. HOWEVER if you are use to driving the vehicle with the altered handling characteristics it is of little consequence.

Finally, the way that I determine the correct tire pressures for my pick up truck is by weighing the vehicle. With myself, a full tank of fuel and the normal bat poop that I carry in the truck I have the truck weighed and record the weight of each axle. Then I have a tire store look up the tire pressure required to support that weight. Just remember to divide the axle weight by two as the weights listed by the tire manufacturer are per tire.

Typically I get 50,000 to 60,000 miles from a set of tires on my Ford F-250 and I replace the tires when there is 3mm of tread depth left. Tire pressure is checked frequently and corrected when the tires are COLD or haven't been driven for 6-8 hours.

[derekh]

MH, I have a Magna wagon and I always run my tyres at 40PSI all round. I believe the car feels lighter for steering, handles better and gives me better fuel economy. I do not have issues with abnormal wear in the centre of the tyre. I say, do it and you'll never run them at the manufacturers recommended pressures ever again.

cheers
Derek

[RETIRED]

The reason that tyre pressures are increased is as David says but more importantly it stops the tyre walls from flexing as much in cornering.

The best improvement (and cheapest) you can make to a cars handling is to increase the pressures by up to 6 PSI. There is no significant increase in ride hardness or tyre wear but it vastly improves the "feel" of the car.

[tea lady]

I like higher pressure in my tyres. I think the car handles better that way, and is less unpredictable. Hubby's car it only pumped up to "handbook pressure" and it rides like a blamonge. (And its a Toyota Echo.:doh:) If I drive it I feel like I can't trust what its going to do. (He did say once that his family had a Valiant Lemon when he was growing up. Could explain his preference.:rolleyes:)

[q9]

On our last car, the tyres needed to be around 38-40 because of the fairly low profile. On the ute, I needed to drop them down from the standard 40 because of the bone jarring shock transfer (driven 98% of the time unladen) and its propensity to spin up the rear inside tyre on any kind of bend. Very exciting when wet...Ute handles much better with lower pressure, than with high, and the car did better with higher pressures. So is all different, no one size fits all.

[billbeee]

I’m another one in the higher pressure than recommended camp.
Travelling long distances in the Territory I once had it explained to me this way. At standard pressures the flexing of the tyre walls helps to increase the temperature and pressure and can lead to blow outs.
10 psi extra stops this happening. I have only ever experienced one high speed blow out (in someone else’s car) and don’t want another.
The extra pressure probably helps the fuel economy too.
Cheers
Bill.

[Greg Q]

The tyre side walls flex too much at stock pressure for you to get the most out of any performance driving course. A beginner learning aggressive steering/braking techniques needs the predictability of a stiffer (higher pressure) tyre.

Running on the road at higher pressures does have its benefits too. Back in the 1974 oil crisis I remember the TV ads which claimed a 6% benefit in lower fuel consumption with higher pressures. All of that heat in the sidewalls has to come from your fuel burn, so the less of that you get the better.