Tire Pressures

[DavidJay]

I intend to upgrade to “E” rated Goodyear Endurance before we begin galavanting around the country next year. It has the original (2014-2015) “D” rated Rainier tires.

I read here on the forum that I should inflate to maximum sidewall pressure, but I have been running 65PSI and the “E” rated GY tires are rated at 80. The supplier publishes a table with load carrying weights at various pressures. Why would they publish the chart if they expected everyone to run max sidewall pressure. Here is the Goodyear inflation chart:

[DavidJay]

Tire size is 225/75R15, load is approximately 2100 lbs max.

[Mopar_Earl]

It's easier to run max pressure. Unless you know the weights for sure and that they are balance left to right, front to rear, you are guessing on your chart pressure. Low pressure makes heat and that kills tires. Max pressure won't harm a tire and won't make it run hot. But will result in a stiffer ride but that's an easy trade off. If you scale each tire and know for sure the weights, then you can inflate to the chart. Though I'd go 5 psi over the chart reading for some safety margin.


Earl

[NewBlackDak]

Originally Posted by Mopar_Earl

It's easier to run max pressure. Unless you know the weights for sure and that they are balance left to right, front to rear, you are guessing on your chart pressure. Low pressure makes heat and that kills tires. Max pressure won't harm a tire and won't make it run hot. But will result in a stiffer ride but that's an easy trade off. If you scale each tire and know for sure the weights, then you can inflate to the chart. Though I'd go 5 psi over the chart reading for some safety margin.


Earl

IF your wheels are rated for it. I have the Endurance tires on mine. Original tires were rated 50PSI, these are rated 80. Wheels are stamped for 65, so that’s what I run.

[Mopar_Earl]

Your wheels should be rated for the tire size, pressure and weight. Dangerous otherwise. People look for the max pressure on the tire side wall, not what the rim is rated it. Rims can be stamped on the backside or inside. Some have no markings at all.


Earl

[oldmanAZ]

The table shows "tire load limits" at various pressures. So it shows the load the tire can carry safely at various pressures. As Earl said, if the load on a tire is higher than estimated, the tire could be under inflated; virtually everyone agrees that is BAD.

Also, the chart shows cold inflation pressures. The tire manufacturer knows increasing temps will raise the tire pressure. They don't say to decrease inflation pressure after driving, so they know that pressures OVER the max on the sidewall are still safe.

The tire manufacturer doesn't know about sway or trailer handling, either. Higher tire pressures give stiffer sidewalls that, IMO, improve trailer handling and lower sway tendency.

As far as harshness, I noticed no change when going from my Rainier tires at 65psi to Endurance tires at 80psi for my TT.

In short, IMO, there are no 'downsides' to running with the max sidewall inflation pressure but are several reasons why it's a good idea to do so.


EDIT: Of course with ANY tire pressure, keep an eye on the tire wear patterns. I also have my TT, and TV, tires rotated and balanced roughly every 5,000mi. Hey, it couldn't hurt and it's free.

[DavidJay]

I did not intend to run at the pressure for 2100, I was considering running at the rated pressure for the “D” rated tire (65PSI) which gives me a 20% safety margin on weight (2500+).

One of my concerns is the ride - I have seen comments about firmer tires shaking up the interior.

[rockaw]

Originally Posted by NewBlackDak

IF your wheels are rated for it. I have the Endurance tires on mine. Original tires were rated 50PSI, these are rated 80. Wheels are stamped for 65, so that’s what I run.

Interesting, My wheels were stamped for 2830, not for PSI.

[oldmanAZ]

Originally Posted by DavidJay

snip...
One of my concerns is the ride - I have seen comments about firmer tires shaking up the interior.

I run 80psi in my TT Endurance tires and did not notice any problem (either visually or in the trailer contents), but DID notice a slight increase in fuel mileage.

BTW, I run 80psi in my tow vehicle rear tires and 75psi in the fronts (for better handling), year round, towing or not. Is the ride harsher than it would be with lower pressures? Probably. But I get very good handling and even tire wear (I have them rotated and balanced for free at Discount Tire every 5,000mi). And, I guess, after 12years and 350,000+mi I'm very comfortable with that.

[in the wind]

Originally Posted by Mopar_Earl

Your wheels should be rated for the tire size, pressure and weight. Dangerous otherwise. People look for the max pressure on the tire side wall, not what the rim is rated it. Rims can be stamped on the backside or inside. Some have no markings at all.
Earl

80 PSI rims need the metal valve stems.
Lower pressure ratings use rubber stems.
What limits the wheel pressure ratings are the valve stems.
So if you want to increase your tire to 80 PSI, install some metal valve stems.

[NewBlackDak]

Originally Posted by in the wind

80 PSI rims need the metal valve stems.
Lower pressure ratings use rubber stems.
What limits the wheel pressure ratings are the valve stems.
So if you want to increase your tire to 80 PSI, install some metal valve stems.

Didn’t know this! I had them install metal stems anyway just for cheap peace of mind.

[fast_st]

The load table is a good thing to have on hand! Higher pressures than suggested will cause center tire tread wear, lower pressures for load will cause excess sidewall flex, over heating and tire failure. You should scale your trailer, get the axle weights and follow the charts.



On long hauls, I'd use a non-contact thermometer and adjust pressures up by 5psi increments on the road to keep temps the same and within limits. Heat from flexing is much more detrimental than excess pressure or weight. Speed also magnifies any overloading/underinflation issues.

[norty1]

You trailer contents are going to shake rattle and roll no matter what.

A few lbs more or less air won't be noticed. Shocks may dampen some of it.