austinado16

Just back from 288mi. Burned 12.4 US gallons and stayed at the speedlimit, either 55 or 65, depending on what highway we were on.

So that's 23.2mpg, but I'm going to step out a limb and say we probably get 24mpg because we had some short hop city driving, and some steep grades to climb, and 3 times I got on it pretty good while passing slower traffic.

This was done on premium fuel (91 octane) with the tires aired up to their max pressure of 44psi.

We rolled 210,000mi too.

No CEL's. No spewing coolant. No used coolant.

J@RO

When you hit a pothole your tire might say "Goodbye" @ this pressure... (this pressure + even more pressure from the tire compression = BIG BANG!)

The pressure on the tire basically means that the tire withstands this change without blowing into atomic particles...DANGEROUS MOVE!

Second, you got no traction when driving-breaking. Lower it to ~38 in front and 36 in the back - when driving with two. Or 38x38 when fully packed up.

austinado16

Been running tires at the maximum pressure for decades and have never, ever had a tire failure.

Let me give you a couple of real world examples to back up the hundreds of thousands of miles I've driven like this:

My popup camp trailer runs on 12" high speed trailer tires. They are rated for 80psi and that's where they have to be run or they will generate so much heat they literally blow apart. I've towed this camper to the Grand Canyon 2 summers in a row, 12hs across the central California valley, through the Mojove Desert and through Arizona with outside air temps in the 105-115*F range, pavement so hot you can actually cook eggs on it, and I've measured the tread temp at 145*F. During this time, my Suburban is running 41psi, the max tire pressure it's P235-15's are rated for. Again, that's 12hrs one way.....6,500+lbs of truck towing 2,000+lbs of camper.

If running tires at their maximum pressure caused tire failure, I assure you, I would have experienced it by now.

As for cornering and braking...that's a function of tire sidewall strength, tread design and tread compound. You might argue that harder (more aired up) tires would corner worse because they'll slide......but I'll argue back that aired down tires have sidewalls that mush out, and that it's tread compound that ultimately grabs. Look at motorcycle tires. Aired up super hard, and they are very hard to begin with...you can ride with a flat because they sort of stay up. A soft compound tire will let you drag your knees all day long if you've got the skill. A hard compound "touring" tire will wash out and leave you sliding down the road.

Aired up tires get better mileage, and have a higher hydroplaning speed on wet pavement.

And no, the centers of my tires don't wear out first. The tires wear perfectly normally.

Buks

I am surprised
All sedan car manufacturers recommend tyre pressures of 2.0 to 2.6 bar which is roughly 30 to 38 PSI
These pressures are supposed to give the most comfortable ride quality without sacrificing safety and the tyres stay within the temperature limits set by the manufacturer
Very confusing to say the least

regards
Buks

austinado16

Sort of like putting a warning on a plastic bag saying "Don't let children put this over their head"

kday

In general a lower tire pressure will improve grip by increasing the size of the contact patch. This can be used to tune the oversteer/understeer balance of the car by adjusting the front and rear tire pressures separately.

For passenger car applications, running tires at the max pressure will improve mileage at the expense of ride quality and handling.

austinado16

I can only speak for how I drive, and how my family wants to be driven. I don't drive in a way where I need the marginal better traction that my hard rubber compound tires are lacking to begin with. The coefficient of friction between the tire and the road is going to be the standard .07 plus or minus a very small amount depending on new or old pavement, concrete versus asphalt, sand on the surface, oil on the surface etc.

And hey, I'm not saying that anyone else should do this. I'm also not going to say that doing this is going to cause a firey car crash and you'll have nothing to blame but that extra 5psi in your tires.

Melinko bq

Tire should never blow up over normal driving surfaces and conditions. If you hit a pothole the size of China, I would bet money that the wheel would bend and 'rapidly deflate' the tire before tire 'blew up'. Tire might break a few steel chords inside at point of contact, but still hold air... Witnessed lots of these from potholes ---> Wheel deformed beyond use while tire still held air to max pressure and beyond (sometimes need 100+psi in order to seat the bead, usually on Z rated still w/ 44 psi max).

Some merit to the 'wider footprint' argument, but not valid during sliding as surface area not a variable in kinetic friction. If you'll be driving through lots of snow, deflate tires a bit to allow them to deform easier. On a road trip - bump them up to max for the gas mileage (minimizing deformation = uses energy). Very safe to have a tire at the max pressure, lots of factor of safety involved...

In the end, I would set the tire to whatever pressure within range that balances comfort and mileage to the desired. Mine's usually at max.

austinado16

And I understand there are all sorts of things that factor into tire performance and handling, but again.........we're talking about a passenger car being driven normally. We're not talking about flogging a car around a race track where every drop of torque, horsepower and traction comes into play.

kday

This is true in a physics book, but practical vehicle dynamics are more complex. The rubber meeting the road is not reducible to "mu" alone.