Tire Pressure; condensed information

[lightfoot]

Originally Posted by Christofoo

My tires say:
MAX LOAD 510 kg (1124 LBS)
AT 300 kPa (44 PSI) MAX PRESSURE

To me that translates as "44 PSI is the correct pressure for the max load of 1124 lbs, and 44 PSI is the max pressure".

Chris

Just checked the Prius tires and they have separate Max Load and Max Pressure listings printed about 3" apart on the sidewall, no "@" between then. Go figure.

I'm running them at 44psi no problems. Worked fine when I had to do a "brake test" in heavy rain last night and again in the dark this morning when pedestrians suddenly appeared at ped xings that lack traffic lights. (why are raingear and umbrellas black rather than white or reflective???).

[CapriRacer]

Originally Posted by lightfoot

Is there any published hard data confirming that there is an issue in real-world use at substantially higher pressures than placard, either (a) at sidewall or (b) above sidewall?? We have a limited amount of data from folks here, including me with three vehicles, that running current radials at or above the sidewall pressure number is not a problem and in fact has some distinct benefits........

I was hoping someone else would answer this question - but here goes.

No, there is very little hard data on anything related to pressure above placard pressure on tires. It's pretty much all been anecdotal. That means you need to pay attenttion to what others are reporting. Here's what I have noticed

A lot of folks have reported center wear. There are reports of wet traction issues. Groove wander issues. While there have been reports of failures, it's unclear if the rate is different than the norm - seems to be, but far from clear.

Other issues have been reported, but those issues don't seem to be out of proportion to the rest of the poulation.

[F8L]

Originally Posted by CapriRacer

I was hoping someone else would answer this question - but here goes.

No, there is very little hard data on anything related to pressure above placard pressure on tires. It's pretty much all been anecdotal. That means you need to pay attenttion to what others are reporting. Here's what I have noticed

A lot of folks have reported center wear. There are reports of wet traction issues. Groove wander issues. While there have been reports of failures, it's unclear if the rate is different than the norm - seems to be, but far from clear.

Other issues have been reported, but those issues don't seem to be out of proportion to the rest of the poulation.

I think the narrow tire crowd like Prius owners do not suffer from center tire wear when using increased pressure. Are the reports you read from owners of wider tires?

[herm]

center wear issues are only with bias-ply tires (trucks, trailers etc), radial tires dont suffer from that.. you will often see side wear on radials if the pressures are too low.

[ksstathead]

Zero signs of center wear on the light truck and 3 cars I run at or a little over max sidewall. Have not seen any reports of center wear or any other problems except increased NVH which is real, but mitigated by slower, more aware driving.

These anecdotes are over about 8 years and well over 100,000 miles.

[lightfoot]

Originally Posted by CapriRacer

It's pretty much all been anecdotal.

OK, here are three anecdotes to add to the pile:
(1) 2003 Subaru Outback wagon, Nokian All Season Tires run at sidewall (51psi) - didn't notice any uneven wear but I didn't have a tread depth gauge - wet braking fine, steered quicker, didn't notice any changed in ride even going from 30-something placard directly to 51psi in the same day - sold car before the tires were worn out
(2) 2006 Honda Insight MT, Bridgestone Potenzas, 44psi sidewall run at 65psi - original set replaced at 62,000 miles when they still had wear well beyond the minimum recommended, but I was concerned about availability of replacements - measured tread depth with a gauge, tread remaining was if anything deeper (less wear) in the middle than at the sides - again no problems with braking, handling, or ride
(3) 2011 Prius - OEM Goodyears run at sidewall (44psi) - haven't checked wear because I have only about 12k miles on the car - tested emergency wet braking in pouring rain several nights ago to stop for darkly-clad pedestrians on crosswalks, no problems (hit antilock once) - handling and ride are both fine

[PaleMelanesian]

Originally Posted by CapriRacer

A lot of folks have reported center wear.

citation?

[diamondlarry]

Originally Posted by CapriRacer

A lot of folks have reported center wear.

Originally Posted by PaleMelanesian

citation?

Yeah, I'd be interested in that citation/link too...unless it's "just" anecdotal.

[CapriRacer]

Originally Posted by PaleMelanesian

citation?

Rather than fill the page with links, I've selected just a few.

http://www.cleanmpg.com/forums/showt...t=41754&page=2

waltermlee reports wet traction loss. He might also be reporting tread separations, but it is unclear.

http://www.cleanmpg.com/forums/showthread.php?t=37220

Some other Dave reports new tires breaking loose at 50 mph.

http://www.cleanmpg.com/forums/showthread.php?t=22901

npauli reports traction loss

http://www.cleanmpg.com/forums/showt...=10881&page=11

Corvette reports center wear on his rear tires.

http://www.cleanmpg.com/forums/showt...t=25859&page=7

Racer reports center wear at 40 psi (norm is 32!)

http://www.cleanmpg.com/forums/showthread.php?t=19495

[herm]

note that LT tires are usually bias ply and should be used at very high pressures.. pickups and cargo van use those due to their load carrying ability, most 18 wheeler tires are also bias ply. When you see a R (radial threads) in the tire designation that means Radial construction, D (diagonal threads) stands for bias-ply, and B means belted, a reinforced bias ply type. Never ever confuse truck tires with car tires..

Bias-ply tires will bulge out at the center with higher than required pressure, load will flatten them out again.. radial ply tires are very resistant to bulging out, loaded or not.