New tires, PSI question

[Old_Stevenick]

I'm sure this has been asked and I did try the search function, but...

1650 Bullet Crossfire. 225/75/15 tires.

I bought a pair of Carlisle Radial Trail HD Trailer Tires.

Shop inflated them to 80PSI.

I'm concerned that the rims can't handle that much pressure. Should I lower them to 60 or 65 PSI?

[chuckster57]

Your rims should have a max inflation number, maybe stamped on the backside, what does the sidewall of the tire say?

[wiredgeorge]

Originally Posted by Old_Stevenick

I'm sure this has been asked and I did try the search function, but...

1650 Bullet Crossfire. 225/75/15 tires.

I bought a pair of Carlisle Radial Trail HD Trailer Tires.

Shop inflated them to 80PSI.

I'm concerned that the rims can't handle that much pressure. Should I lower them to 60 or 65 PSI?

I have a 2002 Cougar with the same size tires and use the Carlisle 80PSI. I have used 80 PSI in those tire since owning the camper (several years). I have never heard of a person going from LRD to LRE and the rim blowing up.

[bsmith0404]

That’s something I would have checked prior to buying the new tires. In theory the LRE has a stronger sidewall than the LRD which allows it to hold the higher air pressure, but running it with 65 psi still gives it the same load carrying capacity as the LRD.

From what I’ve seen, if the wheels are 6 bolt, they’re probably rated for 80 psi, if they’re a 5 bolt, most likely 65. That is not written in stone and by no means a way to determine for sure. You need to pull the wheel and check the back, or at least check the manufacturers website for specs on your wheel.

[Old_Stevenick]

I looked at the rims and they don't say maximum PSI. They do say maximum load of 2,830.

How about 70PSI, does that seem good?

[Old_Stevenick]

The sticker on the trailer says D rated tires inflated to 65PSI Cold.
These are E rated tires with a maximum of 80PSI Cold.

Suggestions?

[CWtheMan]

Originally Posted by Old_Stevenick

The sticker on the trailer says D rated tires inflated to 65PSI Cold.
These are E rated tires with a maximum of 80PSI Cold.

Suggestions?

The minimum safe inflation pressures for your new tires is 65 PSI.

The same sized tires with a LRE provide an identical load capacity at the recommended cold inflation pressures found on the trailer tire information placards.

However, the OEM provider is only required to meet the maximum load capacity of the OE tires with the wheel and valve stem specs.

If you cannot find that information on the wheels/stems find out who the OEM provider was for your trailer and ask them or check their OEM wheel specs.

OEM provider information can be found on page #19 of the owner's manual link below.

https://keystone-rv-dealer-app.cdn.p...2+10-27-21.pdf

[Old_Stevenick]

I emailed Keystone to ask. That chart only list tire, not wheel OEMs, probably best to see what Keystone says.

The wheels do show a load capacity of 2,830.

[CWtheMan]

Originally Posted by Old_Stevenick

I emailed Keystone to ask. That chart only list tire, not wheel OEMs, probably best to see what Keystone says.

The wheels do show a load capacity of 2,830.

Then they are certified to 80 PSI. However, I'd still want to insure I had steel valve stems.

[Old_Stevenick]

Thanks, how would I insure that?

[Old_Stevenick]

Tire shop just told me they are "half brass" stems which are rated for high pressure.

With all this in mind, should I leave them at 80PSI or maybe deflate them a little to be safe. 70 or 75?

[CWtheMan]

Originally Posted by Old_Stevenick

Tire shop just told me they are "half brass" stems which are rated for high pressure.

With all this in mind, should I leave them at 80PSI or maybe deflate them a little to be safe. 70 or 75?

I recommend they be inflated to a PSI value that will allow them to provide a load capacity reserve 15% above vehicle certified GAWRs.

the typical brass/rubber valve stems allow inflation pressures to 100 PSI.

https://www.usafleetsupply.com/prodd...bber+.453+Hole

[Tireman9]

Originally Posted by Old_Stevenick

Tire shop just told me they are "half brass" stems which are rated for high pressure.

With all this in mind, should I leave them at 80PSI or maybe deflate them a little to be safe. 70 or 75?

I strongly recommend that ALL RVs use Bolt-in metal valve stems. The "Half metal are actually just snap-in rubber that can flex or fail. When you run "Hi-Press" rubber valve stems you can end up like this.
https://youtu.be/G-R3-MNaFB4


Some will sell rubber stems that have thin chrome sleeve and try and tell you they are metal. You need to look for the hex nut and threads to know they are actually metal "bolt-in" stems.

[Old_Stevenick]

GVWR is 4,700. 15% above that is 5,405. ½ of that is 2,702.

According to one of the charts linked to on the forum that would be 75PSI.

Sound good?

[CWtheMan]

Originally Posted by Old_Stevenick

GVWR is 4,700. 15% above that is 5,405. ½ of that is 2,702.

According to one of the charts linked to on the forum that would be 75PSI.

Sound good?

Certified vehicle GAWRs are used by to RV trailer industry for the purpose of tire selections and load capacities.

[JRTJH]

Probably ought to start with what size/load range tires you installed ???

Depending on how much "overkill" you bought, the recommended pressure, which is directly rated to load carrying capacity, would be "required to meet the load".

On the other hand, most people buy tires to obtain increased load capacity (for safety reasons).. If so, why "air them down to the level of the old tires and eliminate any increased capacity" ?????

[Old_Stevenick]

4400 lbs GAWR per axle.
2200 lbs per tire
2530 lbs is 15% above this.

Chart now says 65PSI.

Great info from you, thanks, but I'm still unsure what to do.

[CWtheMan]

Originally Posted by Old_Stevenick

Attachment 40774

4400 lbs GAWR per axle.
2200 lbs per tire
2530 lbs is 15% above this.

Chart now says 65PSI.

Great info from you, thanks, but I'm still unsure what to do.

Remember, 65 PSI is the minimum safe inflation pressures for your tires. Anything between 65 PSI and 80 PSI is optional.

Soon after the RVIA recommended 10% load capacity reserve for RV trailer tires was established, Keystone got onboard and a great improvement in tire reliability was noticed when 10% or more load capacity reserves were added to OEM tire installations.

[jadatis]

Originally Posted by Old_Stevenick

Attachment 40774

4400 lbs GAWR per axle.
2200 lbs per tire
2530 lbs is 15% above this.

Chart now says 65PSI.

Great info from you, thanks, but I'm still unsure what to do.

Remarkeble is the enormous reserve of the axles( 2*4400lbs =8800lbs) to the GVWR of 4700 lbs
GVWR filled in in my made extra safe calculator, and maxload tires reduced by 6 Loadindex steps, gave only 37 psi.
The 4400lbs an axle gives 82 psi with max reserve without bumping.

But I daubt you ever using axles to the max if you dont overload the GVWR.

Lets rediculesly assume 4800lbs total weight, and zero lbs on the pin. And a division between the axles 1/2.
Then one axle 3200lbs and the other 1600lbs.
Far away from 4400lbs, even the highest loaded.

To make it complete also for the D-load tires

GVWR 4700 filled in 34.psi
GAWR 4400 x2 filed in 75psi, so 10 psi more then the reference pressure of 65 psi.
GAWR filled in and 2540 lbs a tire used, so no 6 LI steps lowered, 63 psi.

I give it both, because most dont apriciate my pigheaded system.

But my idea is that even with the old tires at 65psi some screws trembling loose.

And the enormous reserves of the axles, makes them stiffer, so lesser comfort.

Weighing is the only way to be shure

But my carefull opinion is that 80 psi is not needed, and even 65 psi is, if not higly overloaded, could give screws trembling loose.

[bsmith0404]

Originally Posted by jadatis

Remarkeble is the enormous reserve of the axles( 2*4400lbs =8800lbs) to the GVWR of 4700 lbs
GVWR filled in in my made extra safe calculator, and maxload tires reduced by 6 Loadindex steps, gave only 37 psi.
The 4400lbs an axle gives 82 psi with max reserve without bumping.

But I daubt you ever using axles to the max if you dont overload the GVWR.

Lets rediculesly assume 4800lbs total weight, and zero lbs on the pin. And a division between the axles 1/2.
Then one axle 3200lbs and the other 1600lbs.
Far away from 4400lbs, even the highest loaded.

To make it complete also for the D-load tires

GVWR 4700 filled in 34.psi
GAWR 4400 x2 filed in 75psi, so 10 psi more then the reference pressure of 65 psi.
GAWR filled in and 2540 lbs a tire used, so no 6 LI steps lowered, 63 psi.

I give it both, because most dont apriciate my pigheaded system.

But my idea is that even with the old tires at 65psi some screws trembling loose.

And the enormous reserves of the axles, makes them stiffer, so lesser comfort.

Weighing is the only way to be shure

But my carefull opinion is that 80 psi is not needed, and even 65 psi is, if not higly overloaded, could give screws trembling loose.

FYI, he only has one axle on the 1650 Bullet. Not nearly as much room for error as you were thinking.