What tire pressure should I run?

[ptjones]

Wider tires aren't good for gas mileage. Higher tire pressures improve MPG's, but with the potential of center wear. I go for the highest pressure and still get even tire wear.

Paul

[CapriRacer]

Originally Posted by ptjones

Wider tires aren't good for gas mileage. .......

Not exactly. Anything the increases the load carrying capacity of a tire helps. I go into more detail here:

Barry's Tire Tech

[ptjones]

If you take a look at EPA # for KIA NIRO there is a 6mpg difference between narrow tires and wider.
Hyundai Ioniq there is a 5mpg. difference.
Brand of tire can also make a big difference. TireRack did a test of LRR tires and Michelin Energy Savers were the best.

Paul

[ksa8907]

Originally Posted by Prophecy99

i did 44 psi for a long time, it worked fine, def stiff, and less grippy,
but on my summer shoes 18x7.5 35mm
i then switched from tires 225/40/R18 to 235/45/R18 both had 50 psi max on sidewall

and by having the 44psi and the extra wider tires, i got horrible center wear. i am currently affraid to go much higher than 38 at the moment w this size, to keep my tires nice and enjoy more grip and softness.

no center wear issues on the old tire size though.

so all this calculation stuff seems legit

I have 235/50/18 with no excess center wear. My wife's 255/65/18 have shoulder wear even at 5psig above placard recommendation. There is more to it than pressure alone.

[Prophecy99]

Originally Posted by ksa8907

I have 235/50/18 with no excess center wear. My wife's 255/65/18 have shoulder wear even at 5psig above placard recommendation. There is more to it than pressure alone.

this was my point too, this calculation stuff is legit, i am intersted in doing it. to find out mine

do u have wheel widths on those for comparison? maybe theres a pattern.

my example was 18x7.5

only thing i changed was tire size and then got bad wear results w the 44psi. it was interesting.

[Prophecy99]

Originally Posted by EcoCivic

Great point about wear on the suspension parts from the bumps/vibration, But maybe if I ran the recommended 30 PSI in the tires the suspension would still be original and in good shape.

No

[Prophecy99]

Originally Posted by Gasoline Fumes

A quick answer would be 45 PSI. That's what I put in the tires on my mother's Prius.

Longer answer:
Go ahead and experiment! I have 55-60 PSI in my junkyard tires. They last me years and wear evenly. In my experience, some tires will wear out the center at higher pressures. Blizzaks are one example, they don't like high pressures. Others will do just fine. I don't know how much, if at all, I've reduced the tire's traction. I'm pretty sure I have more grip than the smaller original size tires at correct pressures. I'm still on the original shocks, springs and dry-rotted bushings at 239k miles. Ride quality and noise isn't great, but it's a gutted '91 Civic Wagon.

this may be legit a point too !! who knows how the tires design reacts to max psi territories.

[Prophecy99]

Originally Posted by JockoT

I had extremely low profile Dunlop Denovo run flat tyres on a car, many years ago. They were very soft, gave phenomenal grip, and were worn out by 10000 miles. Of course, the extra grip made you want to use it, which didn't help with the wear!

how low? no size, no proof,

[JockoT]

It is almost 40 years since I parted with it but they were either 185 or 195 x 50 or 55.
Not wide today but for 1970's UK, they were wide. Here's a snap.

[gone-ot]

A 'wide' tyre spreads the weight across (perpendicular to) the direction of travel.

A 'narrow' type, still has some width, but tends to spread the weight more fore/aft (in the direction of) the direction of travel.

There's a 'cross-over' point where the AREA (width×length) of the tyre's 'contact patch' with the road surface reaches a minimum value: That's good for LRR but bad for braking.

Overall, a physically wide tyre presents a larger AREA of resistance than does a narrow tyre; so aerodynamically, a narrow type is better than a wide tyre of equal diameter.

Considering BOTH aero- and pavement (frictional) losses, the narrower tyre presents a smaller aerodynamic and frictional loss than does an overly wide (ala' drag racing slicks) tyre; but, without moving upward to a larger diameter wheel to regain equality in the total fore/aft contact area, the risk of reduced braking ability becomes a problem.