Yep, another tire pressure discussion...

**Scott'n'Wendy** · 04-27-2022, 07:13 PM

Originally Posted by Captcolour

I always inflate all tires to the maximum cold pressure inflation found on the tire sidewall.

Me too. 80PSI like the really large wording on the sidewall. That's the strongest way to run the tire. My truck runs on 80 psi as well. Rides fine.

**Chickenwarrior** · 04-27-2022, 07:57 PM

I have a 2014 GD momentum and the tire maximum pressure says 123 psi. The sticker on the side also says 123 psi. I’ve glanced over old threads and I sure don’t see many people talking about running this high of tire pressure. When I bought it 2nd hand the tires all had about 85 psi in them and I ran then as is for the trip home. Any experience with these tires? 215/75R 17.5

**bjlakatos** · 04-27-2022, 08:16 PM

Originally Posted by Riverbug

...What would be the benefit for the manufacturer to suggest what seems to be seriously under inflating tires?

Totally agree...seems to me there should be a minimum inflation spec for any tire that would prevent self-distruction. After that have inflation tables up to the max capacity of the tire.

**CoChris** · 04-27-2022, 11:15 PM

Originally Posted by Chickenwarrior

I have a 2014 GD momentum and the tire maximum pressure says 123 psi. The sticker on the side also says 123 psi. I’ve glanced over old threads and I sure don’t see many people talking about running this high of tire pressure. When I bought it 2nd hand the tires all had about 85 psi in them and I ran then as is for the trip home. Any experience with these tires? 215/75R 17.5

Simply put, you have load range H tires. They will say "Load range H" molded into the sidewall of the tire. They are heavy duty (higher load capacity) and require higher pressure to achieve their full load capacity. I think that Grand Design offered Goodyear G614 H rated tires as an extra cost option on the earlier Momentums and Solitudes. You have a very heavy (almost 20,000# GVWR) two axle trailer. The load capacity is greatly reduced at 85 PSI and, in my opinion, will be way overloaded. The lower pressures you see some people running are on much lighter trailers and lower capacity tires.

I would also suggest you check the date code (four digit number) on the tires. Many people recommend replacing them within 5 years of manufacture. Sooner if there is any signs of dry rot, checking or any signs of tread separation. If these are original equipment, they are 8+ years old.

Chris

**Captcolour** · 04-28-2022, 07:30 AM

Originally Posted by Chickenwarrior

I have a 2014 GD momentum and the tire maximum pressure says 123 psi. The sticker on the side also says 123 psi. I’ve glanced over old threads and I sure don’t see many people talking about running this high of tire pressure. When I bought it 2nd hand the tires all had about 85 psi in them and I ran then as is for the trip home. Any experience with these tires? 215/75R 17.5

My 17.5" Coopers Load Range H have a cold pressure inflation of 125 psi. That's what I run in them.

**Chickenwarrior** · 04-29-2022, 06:03 AM

Originally Posted by CoChris

Simply put, you have load range H tires. They will say "Load range H" molded into the sidewall of the tire. They are heavy duty (higher load capacity) and require higher pressure to achieve their full load capacity. I think that Grand Design offered Goodyear G614 H rated tires as an extra cost option on the earlier Momentums and Solitudes. You have a very heavy (almost 20,000# GVWR) two axle trailer. The load capacity is greatly reduced at 85 PSI and, in my opinion, will be way overloaded. The lower pressures you see some people running are on much lighter trailers and lower capacity tires.

I would also suggest you check the date code (four digit number) on the tires. Many people recommend replacing them within 5 years of manufacture. Sooner if there is any signs of dry rot, checking or any signs of tread separation. If these are original equipment, they are 8+ years old.

Chris

Thank you for the reply. Yes they are the original tires. We do not make many trips in this camper, and if we do they are very short, so I haven't considered replacing them yet. It is a Triple Axle Trailer. That being said, you recommend inflating to the full cold rating of 123 PSI? Yes?

**Jerryr** · 04-29-2022, 06:13 AM

Originally Posted by Chickenwarrior

Thank you for the reply. Yes they are the original tires. We do not make many trips in this camper, and if we do they are very short, so I haven't considered replacing them yet. It is a Triple Axle Trailer. That being said, you recommend inflating to the full cold rating of 123 PSI? Yes?

8+ year old tires should be retired even though your trips are short. A blow out will cause damage in the range of $3,000+ to the trailer.

With new H rated tires then air them up to what the sticker on the trailer says.

**Chickenwarrior** · 04-29-2022, 06:22 AM

Originally Posted by Jerryr

8+ year old tires should be retired even though your trips are short. A blow out will cause damage in the range of $3,000+ to the trailer.

With new H rated tires then air them up to what the sticker on the trailer says.

Thank you for your reply. I'll start looking at tire options.

**CoChris** · 04-29-2022, 07:50 PM

Originally Posted by Chickenwarrior

Thank you for the reply. Yes they are the original tires. We do not make many trips in this camper, and if we do they are very short, so I haven't considered replacing them yet. It is a Triple Axle Trailer. That being said, you recommend inflating to the full cold rating of 123 PSI? Yes?

This is an ongoing debate, with lots of "discussions" on the forums here. With a triple axle trailer, you have a lot lower loading on any given tire then a dual axle. The advantages (to my thinking) of running reduced tire pressure
1) is a smoother ride.
2) May get better mileage (tread life) from the tires due to less crowning of the tire - but I have heard of very few people (anyone?) that "wears" a set of tires out before they age (5 years?) out, unless there is an alignment issue.
3) It sounds cool to "custom tune" your trailer for your exact load. OK, a little smartalec but I swear that it what drives some decisions.

The advantages to run the manufacture specified cold pressure is

1) It is what the designers of the trailer recommend
2) This is almost always the (maximum) pressure the tire manufacture recommends
3) This gives you the maximum load capacity, and if you are not loaded to the max, it gives you the most load margin
4) This gives you the lowest rolling resistance and the best gas mileage (probably worth 0.00001 MPG, but we are not in this for economy, right?).
5) This gives you the stiffest tires. I think this give a little less sway, follows the road better and lower tire temps (see #4 ) - all good things in my opinion.

I am not a tire engineer, but I personally run what the factory recommends. Others will probably weigh in (as I said, it is a major topic of discussion) on their preference. It is really up to you and what you want to do.

PS I feel 85 is way, WAY, WAY to low a pressure for those tires, even with no load. Just my opinion and worth way you paid for it.

PPS as @Jerryr said, at 8+ years old, those tires should be replaced. Tire blowouts are no joke and do a lot of expensive damage as well as potentially endangering multiple people.

Wishing you safe and happy travels

Chris