Potential fuel economy gains between 44 and 51 PSI? New tires choices.

[FrugalFloyd]

Good choice. There've been discussions convincing me there's no difference in tires bearing sidewall maximums of 44 and 51 psi. Three mfrs (Michelin is one) use 44 psi as their sidewall max. You can run 51 psi in them w/o problems.

[theholycow]

Barry's Tire Tech is an excellent, educational website on tires.

http://www.barrystiretech.com/loadtables.html

I want to draw your attention to note #3 and the table that follows:

This note means that in spite of the load curve ending at 35 (or 41 for XL) psi, it is permissible to stamp the sidewall of the tire as having a maximum inflation of 35 psi, or 44 psi or 51 psi. (41 or 50 psi for XL).

If you were to dig to find the US regulation that covers what is supposed to be stamped on the sidewall of the tire (In this yearbook, it is FMVSS109, but this was superseded by FMVSS139 in 2007, but this part reads the same for both), the regulation is unclear which of those values it is supposed to be.

Most everyone in the tire industry reads the regulation that either 44 psi or 51 psi is the proper value for SL tires. However, a few tire manufacturers - notably the Michelin group (Michelin, Uniroyal, and Goodrich) have interpreted this differently and read the regulation to mean that for S and T speed rated tires, 35 psi should be stamped on the sidewall, while H and higher are supposed to read 44 or 51 psi.

That means for otherwise comparable tires, you will find different maximum pressures stamped on the sidewall. This means you SHOULD NOT use the pressure stamped on the sidewall as any sort of reference point, except, of course, what it says - a maximum.
and there are a couple exceptions to that!!

Please note that ETRTO and JATMA have similar notes in their yearbook, except that ETRTO's rated inflation pressure for SL tires is 2.5 bar (36 psi)

[palemelanesian]

For the record, I've done four sets of tires on both my cars at "above placard" pressures. Two on the Odyssey at max sidewall (one 44 psi and one 51 psi). Both wore evenly across the tread. Two on the Civic at "well above" max sidewall. The tread wear was/is dead even across the tread.

I'm convinced that modern steel-belted radials don't do the often-quoted center wear at high pressure. I think it's because the steel doesn't stretch much. Low pressure and they do cave in a bit and wear the shoulders, but they stay flat at any pressure above "fully inflated". In my experience, fully inflated is above placard and somewhere close to sidewall max. (32 = underinflated, 35 = underinflated, 44+ = fully inflated)

[IndyFetch]

I had a set of Michelin Destiny tires on my VX. After 40,000 miles, they were less than 1/3 of the way worn. They handled quite well, were not prone to squealing, and offered decent wet and dry grip. The open tread blocks on the shoulders gave great grip in snow at the expense of a little bit of tire hum. I really liked mine, and I hope you have the same luck.

[palemelanesian]

I'm running Destiny's on mine right now. They're noisy, but otherwise I like them.

[theholycow]

Originally Posted by PaleMelanesian

I'm convinced that modern steel-belted radials don't do the often-quoted center wear at high pressure. I think it's because the steel doesn't stretch much. Low pressure and they do cave in a bit and wear the shoulders, but they stay flat at any pressure above "fully inflated".

Well said. I have had center wear, but never severe enough to be worth much discussion; I don't think most people would notice it and I don't think it's what people think of when we talk about it. I agree with your theory about why.

In my experience, fully inflated is above placard and somewhere close to sidewall max. (32 = underinflated, 35 = underinflated, 44+ = fully inflated)

Also well said!