How to, trailer tire pressure ?

[OtisBlkR1]

I can update this tomorrow with exact information, my utility trailer is a 6x10 foot and will be going on a road trip shortly (mentioned plenty in other threads) Ive been surfing the new and im finding a slew of information, although opinions seem to vary.. This trailer will be going 500 miles and will have approximately 1,200 lbs on it.

there seem to be 2 camps Run 50 psi cold without question all the time..

and #2 adjust you tire pressures down according to the load..

Im going to the RV shop Thursday and have many questions for them and this is one i will ask. Im just curious what the general BITOG opinion on the topic is ?

 

[cchase]

I always default to higher is better, since deformation is a major cause of heat which is usually what kills trailer tires.

 

[The_Jeff]

Keep your wheel bearings greased and there won't be as much heat going into the tires. Maybe track them with an IR gun.

 

[gaijinnv]

Originally Posted By: OtisBlkR1
I can update this tomorrow with exact information, my utility trailer is a 6x10 foot and will be going on a road trip shortly (mentioned plenty in other threads) Ive been surfing the new and im finding a slew of information, although opinions seem to vary.. This trailer will be going 500 miles and will have approximately 1,200 lbs on it.

there seem to be 2 camps Run 50 psi cold without question all the time..

and #2 adjust you tire pressures down according to the load..

Im going to the RV shop Thursday and have many questions for them and this is one i will ask. Im just curious what the general BITOG opinion on the topic is ?


What size are the trailer tires?

What is the Max Load and Max psi embossed on the tire sidewall?

How much does your trailer weigh when it is empty?

 

[OtisBlkR1]

Originally Posted By: gaijinnv
Originally Posted By: OtisBlkR1
I can update this tomorrow with exact information, my utility trailer is a 6x10 foot and will be going on a road trip shortly (mentioned plenty in other threads) Ive been surfing the new and im finding a slew of information, although opinions seem to vary.. This trailer will be going 500 miles and will have approximately 1,200 lbs on it.

there seem to be 2 camps Run 50 psi cold without question all the time..

and #2 adjust you tire pressures down according to the load..

Im going to the RV shop Thursday and have many questions for them and this is one i will ask. Im just curious what the general BITOG opinion on the topic is ?


What size are the trailer tires?

What is the Max Load and Max psi embossed on the tire sidewall?

How much does your trailer weigh when it is empty?


max psi is 50 on sidewall

trailer weight is between 850lbs

although i dont have exact numbers they are trailer tires on 14-15 inch rims. can post up after midnight what exact size is.

 

[stockrex]

do max sidewall

 

[WishIhadatruck]

Most trailers have barely adequate tires with regard to size and load capacity in my experience so it usually pays to go max sidewall pressure unless you know you are very lightly loaded. I'd still go max sidewall unless you have delicate cargo you don't want to beat up with higher pressures.

 

[Stewart Fan]

Max them out.

 

[toneydoc]

Trailers beat up stuff all the time no matter what the tire pressure is. Keep it a few pounds below max so that as tires heat up due to load you do not have blow out due to heat build up. That way you are not inconvenieced

 

[fsskier]

Other posters are correct, set them at max pressure (50 lbs) cold. Let the hot pressure go higher, do not let air out. Its the heat that kills them, not the pressure.

Most tire manufacturers list tire capacity as a function of pressure, as the pressure goes down so does the maximum permitted load.

Follow the Goodyear links on Tirerack.com, they recommend filling the Marathon to 10 lbs over the max rating for speeds of 65 mph or more. They make note that this does not increase the maximum load rating but will increase your protection against blowouts.

 

[gaijinnv]

Originally Posted By: OtisBlkR1

although i dont have exact numbers they are trailer tires on 14-15 inch rims. can post up after midnight what exact size is.


Great! When I get the exact size, I can make an informed recommendation.

 

[OtisBlkR1]

Originally Posted By: gaijinnv
Originally Posted By: OtisBlkR1

although i dont have exact numbers they are trailer tires on 14-15 inch rims. can post up after midnight what exact size is.


Great! When I get the exact size, I can make an informed recommendation.


205/15 Herculies trailer tires. Got home last night, forgot, fell asleep..

 

[gaijinnv]

Originally Posted By: OtisBlkR1

205/15 Herculies trailer tires. Got home last night, forgot, fell asleep..


It's OK. I remember what it was like when I had a life ...

Here are my assumptions based on your info:

Tires: Hercules ST205/75-15 6 Ply Load Range C
Max Load: 1,820 pounds @ 50psi
Trailer weight: Approx. 850 pounds
Trailer Load: Approx. 1,200 pounds
Trailer Axles: 1 (Single axle)

Here are the UNADJUSTED tire Load Limits at different Cold Tire Inflation Pressures for a single axle trailer:

@50psi = 1,820 pounds/tire = 3,640 pounds Total Load Limit
@40psi = 1,610 pounds/tire = 3,220 pounds Total Load Limit
@35psi = 1,480 pounds/tire = 2,960 pounds Total Load Limit

These Load Limits/Pressures are only good BELOW 66 mph.

For speeds from 66 mph - 75 mph, you need to increase the unadjusted pressures by +10psi for the same Load Limits.

For speeds from 76 mph - 85 mph, you need to increase the unadjusted pressures by +10psi AND reduce the Load Limits by 10%.

For the sake of discussion (and safety) let's say you are underestimating the trailer weight and the load in the trailer by 20%.

This yields:
Trailer weight of 850# x 1.2 = 1,020#
Trailer Load of 1,200# x 1.2 = 1,440#
Total weight of Trailer and Load = 2,460#

So ... to make a long story a little shorter ...

40psi will carry that load, BUT ...

You will travel above 65 mph with short spurts above 76, so ...

You need to increase the tire pressures to 50psi and reduce the Load Limit by 10%, so ...

@50psi you will have a Load Limit of 3,220# - 10% = 2,898# good up to 85 mph.

So, it is just like several other well-informed folks have advised (but managed to state much more succinctly) ...

Run the Max Pressure of 50psi shown on the sidewall and be happy!

 

[gaijinnv]

Further (don't worry, I'll keep it short) other than assuring sufficient Load Carrying Capacity, running your tires at 50psi has the following advantages:

- Less heat buildup in the tires (leading cause of tire failure)
- Less rolling resistance (higher gas mileage for the tow vehicle)
- Set the pressure and forget it (just look on the tire sidewall if you forget what to set it to)

And in case you are wondering about pressure increase in the tire beyond the max 50psi as the tire warms up - yes, it will increase beyond 50psi, but it is designed to do that. As long as you do not adjust the COLD Tire Inflation Pressure to more than 50psi you are A-OK!

As always, make sure you do not exceed the max load rating for the trailer itself (if it has one marked on it) and do not exceed the max tongue weight or towing capacity of your tow vehicle.

 

[Ken2]

In addition, running the max increases the trailer's stability to cross winds.

In addition to the other good advice above, take a close look at the valve stems. Bend them and look for cracks. Replace any that look questionable.

Hercules is a tire importer and wholesale distributor. Their Power STR radial trailer tire, from the photo, looks a lot like the tire imported and distributed by TBC and labeled Power King and other labels. Maybe not...all Chinese in any case.

 

[OtisBlkR1]

all good info, thank you all.

 

[Colt45ws]

I always put Max cold in. It does slightly increase center wear if very lightly loaded, but in all reality most trailer tires will rot out before they wear out regardless.

 

[OtisBlkR1]

Originally Posted By: Colt45ws
I always put Max cold in. It does slightly increase center wear if very lightly loaded, but in all reality most trailer tires will rot out before they wear out regardless.


true words, no argueing there.