Tires: Tire Pressure, tire placard, winnebago brave

Question
I am using Cooper Tires pn a Winnebago Brave 26 Ft Class A...The tires on the duals are rated at 80lbs.....The plate inside thacab says 55 for the front and60 in the rear....The tire company says run them at 80 lbs....Have have extenders on the back....For the inside tires........The extenders are rubber ones and don't have the braid covering over the rubber....Is that too much pressure for the extenders on the back...????
Thank you ....
Jack h

Answer
Jack,

Let's start with the basics:

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On every vehicle sold in the US - and I understand this is a worldwide practice as well - there is a sticker – commonly called the vehicle tire placard - that lists the original tire size and the proper pressure for that size.  The placard is usually located on a doorpost or in the glove box – but sometimes it is located in the trunk or on the fuel filler door.

BTW, it doesn't matter who makes the tire or what pressure is listed on the tire's sidewall, if the tire size is the same as the placard, then the pressure listed on placard is also appropriate.

One word of caution:  Some trucks use tires with the letters "LT" in front of the tire size - and some trucks use tires with the letter "P" in front of the tire size - and some trucks use tires with the letter "C" after the tire size.  You should not use "P"'s in place of "LT"'s and vice versa.

For this situation, you should be sure the pressure on the sidewall equals or exceeds that pressure on the placard.  If you do this the issue about the letter "C" in the sidewall will take care of itself (which is not true with "LT"'s vs "P"'s.)

If you are using a tire size that is different than what is listed on the placard, then the pressure has to be recalculated.  The calculation is not difficult, but it requires tire load tables which are not allowed to be published in the Internet because of copyright laws.  However, I have a copy and would be glad to do the calculation, but the starting point is the vehicle placard: Tire size and inflation pressure.  I will also need to know the new tire size.

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For your vehicle you should have LT type tires.  Do you?

What does the vehicle placard say about the tire size?  Is it the same as what is on there now?  If so, then the pressure listed on that placard is what should be used, not what the tire company says.

But your question is about the valve extenders - and while I can not be sure who makes the extenders, it is common to use heavy duty hose - and therefore, the hose can stand the normal pressures used for extenders - up to 100 psi!