What PSI for tires?

[way2roll]

After owning a few MH's this is our first FW. Airing up the tires in a MH requires knowing the weights, checking the charts and inflating to tire manufacturer specs. Max PSI was always a no-no as it could affect handling. Is this different for a FW? Is there some place I can find a recommended tire PSI for the FW in my signature? As ambient temps drop I usually find I need to air up all the vehicles a bit. I should also note that my FW tires were filled with nitrogen. That should not be affected as much by ambient temp swings, however I obviously don't have a nitrogen compressor handy. Can I top them off with compressed air? I've never dealt with nitrogen filled tires either.

[Cummins12V98]

New Years is right around the corner. :B

[cummins2014]

ford truck guy wrote:

cummins2014 wrote:

Cummins12V98 wrote:
"Most RV's come with their GVW based on the ties load capacity of the tires they come with. So yes MAX is required. But going from a 3,000# tire to a 4,000# tire and running MAX on both is plain stupid. Why do you think they have weight/inflation charts???

PROPER inflation based on load gives better ride, braking and tire life plain and simple!

Whoa ,and behold ,we agree :B . The thing I noticed is those Sailuns I run ,and now being over tired . They run a bit warmer when I run at 95 psi when cold here in Utah, nothing alarming but warmer. I do this ,because by the time I get to ST George ,Ut where its warmer ,my tires the next morning will be 100 psi or slightly more ,and I don't need to mess with them.

So being 95 cold inflation here in the winter , gives me pretty much the air pressure I am actually wanting year around , although I start out here a bit lower then wanted . I see no issue with that, still giving me 3970 weight rating instead of the 4080 at 100 psi which as said was the OE tire rating .

*** ITS A CHRISTMAS Miracle :B

Miracles never cease to happen :E

[ford_truck_guy]

cummins2014 wrote:

Cummins12V98 wrote:
"Most RV's come with their GVW based on the ties load capacity of the tires they come with. So yes MAX is required. But going from a 3,000# tire to a 4,000# tire and running MAX on both is plain stupid. Why do you think they have weight/inflation charts???

PROPER inflation based on load gives better ride, braking and tire life plain and simple!

Whoa ,and behold ,we agree :B . The thing I noticed is those Sailuns I run ,and now being over tired . They run a bit warmer when I run at 95 psi when cold here in Utah, nothing alarming but warmer. I do this ,because by the time I get to ST George ,Ut where its warmer ,my tires the next morning will be 100 psi or slightly more ,and I don't need to mess with them.

So being 95 cold inflation here in the winter , gives me pretty much the air pressure I am actually wanting year around , although I start out here a bit lower then wanted . I see no issue with that, still giving me 3970 weight rating instead of the 4080 at 100 psi which as said was the OE tire rating .

*** ITS A CHRISTMAS Miracle :B

[cummins2014]

Cummins12V98 wrote:
"Most RV's come with their GVW based on the ties load capacity of the tires they come with. So yes MAX is required. But going from a 3,000# tire to a 4,000# tire and running MAX on both is plain stupid. Why do you think they have weight/inflation charts???

PROPER inflation based on load gives better ride, braking and tire life plain and simple!

Whoa ,and behold ,we agree :B . The thing I noticed is those Sailuns I run ,and now being over tired . They run a bit warmer when I run at 95 psi when cold here in Utah, nothing alarming but warmer. I do this ,because by the time I get to ST George ,Ut where its warmer ,my tires the next morning will be 100 psi or slightly more ,and I don't need to mess with them.

So being 95 cold inflation here in the winter , gives me pretty much the air pressure I am actually wanting year around , although I start out here a bit lower then wanted . I see no issue with that, still giving me 3970 weight rating instead of the 4080 at 100 psi which as said was the OE tire rating .

[cummins2014]

MFL wrote:
Yes, full max 80 psi, when cold. This will keep sidewalls firm, less flex, which results in a cooler running tire. This, part of my reason for not over tiring your trailer, then lowering the pressure. I will add, a truck such as yours, when empty, not towing, you will want to lower rear tire pressure, for better wear, and ride. A TV tire does not have near the sideways scrub of a tandem axle trailer.

Just an FYI, someday when looking at trailer again, what axle should be listed on driver's side front placard of FW. It will also have a sticker on the axle itself, if you feel like crawling under the trailer.

Jerry

Lets push this a bit further here . Am I over tired , yes . Do I run max inflation ,no. Do I have a problem , no. I run off Sailuns inflation chart. My fifth wheel came with Sailun S637 ST235/80/16's from the factory. I now run Sailun S637 ST235/85/16's

As I explained to you in the PM on inflation I use. I want to be at 100 psi cold ,that gives me the same weight rating as the OE Sailuns @ 110 psi. You made me curious about heat difference if I was to run 110 psi instead of the 100. I may do just that for a short trip ,but my guess there is not going to be much difference ,certainly not something to worry about.

[Cummins12V98]

"Most RV's come with their GVW based on the ties load capacity of the tires they come with. So yes MAX is required. But going from a 3,000# tire to a 4,000# tire and running MAX on both is plain stupid. Why do you think they have weight/inflation charts???

PROPER inflation based on load gives better ride, braking and tire life plain and simple!

[MFL]

Yes, full max 80 psi, when cold. This will keep sidewalls firm, less flex, which results in a cooler running tire. This, part of my reason for not over tiring your trailer, then lowering the pressure. I will add, a truck such as yours, when empty, not towing, you will want to lower rear tire pressure, for better wear, and ride. A TV tire does not have near the sideways scrub of a tandem axle trailer.

Just an FYI, someday when looking at trailer again, what axle should be listed on driver's side front placard of FW. It will also have a sticker on the axle itself, if you feel like crawling under the trailer.

Jerry

[JIMNLIN]

Yes run the max sidewall pressures. Most likely a ST235/80-16 E at around 3500 lbs capacity. Four tires gets you around 14000 lbs of capacity on your trailers 14350 gvwr. Donn't mess around with those minimum tire pressure/load charts with those 80 psi E tires and that size trailer.

[way2roll]

Lots of info, thanks. Just to clarify, on the existing tires I should run 80 psi?

Not much info on what axles I have. Description says: DEXTER Safety and Performance Package which includes heavy duty axles with E-Z Lube hubs, Nev-R-Adjust brakes, E-Z Flex suspension

But as we all know that could mean a whole lot of nothing.

[MFL]

JIMNLIN wrote:


OP if your trailer has 7k or even 8k axles the best on the market for price and long term reliability is the S637 Sailun ST G load range which is a commercial grade all steel ply carcass tire made for the service trailer industry. There a long term tire with a long service life and work great on rv trailers.
The S637 in a ST235/80-16 G at 4080 lbs capacity at 110 psi. Just make sure the wheels can handle the higher pressure needed.

While I agree with Jim, on using G-rated tires on 7-8K axles, I highly doubt the OP has more than 6K axles. While it is an important factor, I did not ask OP to check this.

The manufacturers take into account that 20% of total weight will be pin wt, which is on truck, not trailer axles. In this case, about 11,500, if trailer is loaded to full GVWR of 14,350. The tires in the size/rating now used will be rated about 3,500 capacity, so 7K per axle, or 14K total to cover only 11.5K needed capacity. That is about a 3K lb safety margin, which is more than adequate, even though one tire may have to carry a little more than an even share of the wt.

If the OP wanted to use ST235/85R 16E, the capacity would be 3,640, so even more safety margin. This size, not quite an inch more in diameter, but clearance above tire, and between tire needs consideration. Above would only be less than 1/2 inch less clearance, so likely okay. Also to consider, the new F350 will sit tall, and a little taller tire on the trailer will improve the chance of the FW being closer to level when towed.

I would suggest getting the newer, much improved ST tire, such as the Provider (good reviews for about 10 yrs, and one of first improved design, with higher speed rating M) ST235/85R E. The GoodYear Endurance in same size, another good choice (good reviews about 3 yrs.), and American made. Either of these also available in 235/80R 16E, with 1 inch less diameter, if clearance issues.

I will add IMO, it would not make sense to use a G-rated tire, with over 4K lbs capacity per tire, 16K overall, when only 11.5K needed. Some, who choose to do this, will run way less than 110 psi needed for that rating, for a better ride, or because their wheels are not sufficient for 110 lbs.

For best results, I recommend using the proper tire, at full psi available, to cover the max tire capacity.

Jerry

[cummins2014]

JIMNLIN wrote:

cummins2014 wrote:

JIMNLIN wrote:
IMO he doesn't need to read pages of tire jargon
What he will be getting is a broader perspective in answers from a actual tire engineer on this subject with no rude comments.

Not sure what’s rude ,if you are referring to tire jargon , so be it . But with his fifth wheel, GVWR, I’m not sure doing anything but inflating those OE tires to max inflation , and hope for the best , considering there is a good chance they are a cheap ST tire .You might want to elaborate on what more would be gained by reading pages of tire terminology, and still not coming up with max inflation . I’m sure you could condense it to something besides pages of reading .

The rude comments that were made wasn't done by you but was done towards the OP by others.
Your advise to use max sidewall pressures is right on. However Tireman9 blogs goes into tech details why its necessary to do so which the OP may or may not be interested so he or you don't have to read it.

OP if your trailer has 7k or even 8k axles the best on the market for price and long term reliability is the S637 Sailun ST G load range which is a commercial grade all steel ply carcass tire made for the service trailer industry. There a long term tire with a long service life and work great on rv trailers.
The S637 in a ST235/80-16 G at 4080 lbs capacity at 110 psi. Just make sure the wheels can handle the higher pressure needed.

Thanks !!

I totally agree , with his weight . Certainly not another E rated tire , regardless of their overblown weight ratings . Sailun is the logical choice.

[JIMNLIN]

cummins2014 wrote:

JIMNLIN wrote:
IMO he doesn't need to read pages of tire jargon
What he will be getting is a broader perspective in answers from a actual tire engineer on this subject with no rude comments.

Not sure what’s rude ,if you are referring to tire jargon , so be it . But with his fifth wheel, GVWR, I’m not sure doing anything but inflating those OE tires to max inflation , and hope for the best , considering there is a good chance they are a cheap ST tire .You might want to elaborate on what more would be gained by reading pages of tire terminology, and still not coming up with max inflation . I’m sure you could condense it to something besides pages of reading .

The rude comments that were made wasn't done by you but was done towards the OP by others.
Your advise to use max sidewall pressures is right on. However Tireman9 blogs goes into tech details why its necessary to do so which the OP may or may not be interested so he or you don't have to read it.

OP if your trailer has 7k or even 8k axles the best on the market for price and long term reliability is the S637 Sailun ST G load range which is a commercial grade all steel ply carcass tire made for the service trailer industry. There a long term tire with a long service life and work great on rv trailers.
The S637 in a ST235/80-16 G at 4080 lbs capacity at 110 psi. Just make sure the wheels can handle the higher pressure needed.

[Cummins12V98]

When you decide to buy tires I highly suggest GY ENDURANCE.

[cummins2014]

way2roll wrote:
Was able to get up there today. The tires are cheaper ones as suspected. Ridgeway Sport ST 235/80 r16 with an E load range. The sticker says 80 PSI cold. There are 4 tires. The FW's GVWR is 14,350 with UVW 11,414.

I plan on getting decent tires in the spring, but for now these will have to do.

Good plan , in the mean time I wouldn’t run them 1 psi less then 80 cold . And if I may I suggest getting a TPMS .