Toyo Tire Pressure

[Wwdnet]

The sticker inside our 96 Daybreak says 65 psi. We had new Toyo 14-ply tires put on and the dealer filled.them to 105 psi, which he said the manufacturer recommends. How do we know what the correct psi should be? Tires are 225 80R19.5

[LJowdy]

The only true way to know is to weight all corners of the vehicle then find the tire manufacturers tire inflation chart and fill accordingly

[Gary RVRoamer]

Which manufacturer was that dealer quoting? Toyo or Damon? It sounds like the tire sidewall psi value from Toyo, which is most definitely NOT a recommendation by Toyo. And if Damon has a recommendation, it will be on a tire placard adjacent to the driver seat. The psi stamped on the tire sidewall is the MINIMUM psi that will provide the tires maximum rated load capacity (weight). Whether you want or need that much is an entirely different matter.


Are you sure the size is 225/80R19.5? I've not encountered a Toyo like that, or any other brand for that matter. It may be 225/70R19.5 instead. Here is the Toyo commercial tire inflation table.


https://www.toyotires.com/media/2155...ion_tables.pdf


You can estimate tire weight loads using the axle GAWRs, but the preferred method is to get actual scaled weights at a truck scale. The axle GAWRs allow you to calculate the inflation needed for a fully loaded axle, which is sometimes more than what is actually needed but near always a safe bet.


NOTE: The Toyo inflation table for a 225/70R19.5 shows that 105 psi is the max load inflation. Very likely excessively high for your coach.

[Wwdnet]

We lowered the pressure to closer than the placard psi. I checked the chart so I think we're okay now. There are no weigh stations or truck services close to us, so we can address the weight on each corner once we go further.

[Gary RVRoamer]

Assuming the tires are the size shown on the placard in the coach, use the placard psi and you will be safe. If the coach is loaded less than it maximum weight (GVWR), the placard values may be a bit higher than strictly necessary but that's a minor thing, mostly just a bit harsher riding.

[beenthere]

just use math.. weigh coach front n rear. say front is 10000 # so each tire holding 5000#. tire rating says holds 7500# at 120psi.. so 7500 divided by 120 = 62.5#'s per psi. so 5000# divided by 62.5 = 80 psi inflated to hold your 5000# weight.. and it works safely. and those that disbelieve, just check you tire manufactures page then do the math see its there.
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[hardint]

Mine steers better at 85 - 90 psi.

[beenthere]

if ur reffering to my math ,,that was just an example of weights. of course you have to weigh and read tire info to get true figures, by the way my fronts have to be at 105psi

Originally Posted by hardint

Mine steers better at 85 - 90 psi.

[Crasher]

Unfortunately, too many tire dealer/techs don't have a clue as to what the correct tire pressure is for any motorhome. If they do not ask what the weights are or look at the placard, then they are not qualified to set the psi. All many of them know, is to inflate to the max listed on the tire. Just another reason for RV owners to educate themselves regarding the operation of their unit.

[Gary RVRoamer]

Crasher is on-target. The tire dealer/techs default to the tire sidewall psi so they cannot be accused of "under-inflation" if you have a problem later. They don't have weights and aren't about to make assumptions about tire loads, so they go for the max. Most of them will use a different psi IF you put it in writing on the work order, though.


One of these days some tire shop will get sued for grossly over-inflating a tire and procedures will than change, but until then you need to educate yourself enough to specify the pressures you want when you change tires. The coach builder's federal tire placard should be your starting point.

[Milford 47]

Originally Posted by Wwdnet

We lowered the pressure to closer than the placard psi. I checked the chart so I think we're okay now. There are no weigh stations or truck services close to us, so we can address the weight on each corner once we go further.

I had that tire on my F550 flat bed KR for quite a few years

Seems like the sidewall psig was 115 or something like that and we ran the max since we pulled 32 foot or larger tandem trailers

Watch your tire temperatures on a very hot day and adjust accordingly since you are well below the minimum setting

[jlmanatee]

I've used the attached Toyo document to help figure this out. While it would be best to get weight measurements from all four corners of the vehicle, I have just used the per-axle weights from a recent Cat scale weigh. For my 22.5" tires I'm using 85 psi all the way around.

[Domo]

I always ask my salesman what PSI to run.

That way I get to laugh all day long...