Community Forums

Bob King · 07-02-2010, 07:21 PM

This regards Tire temps and pressure s.
I have a 2005 Hurricane 32R. The tires are 245/70/19.5Rn I run the tires at about 78 lbs cold. The other day, July 1st, I stopped at a rest area on I-40 West of Needles, CA and while there checked the tire temps. They ranged from 152 to 165 degrees F. The inner duals were the hottest. The Outside air temp was 104 Degrees. I have no idea what is normal, and did nothing about it. Out of curiosity, I checked the pressures and they were all in the 95 to 98 lbs area. Next morning, the temps were normal as was the pressure. I do know that pressure goes up with temp., but again have no idea how much.
Anyone have any thoughts or suggestions?
Thanks
Bob

DriVer · 07-02-2010, 08:51 PM

Quote:

Originally Posted by Bob King

Anyone have any thoughts or suggestions?

Bob, See the TST Thread here in the Vendor Spotlight. Dan Covington from TST hosted a Chat session here last Wednesday in the RV Technical Chat Room.

You can always call their Techs and discuss any of your concerns and they will walk you through pressure and temperature. I would expect that different temperatures will be present on duals if they are not identically inflated. I use a Crossfire!

NeilV · 07-07-2010, 04:00 AM

Bob,

Crown in the road can also cause the inners to run hotter as could having new and old tires paired on the duals. The newer tire may be a half inch or so greater in diameter so it will end up bearing a greater part of the load and run hotter. However the smaller tire may be slipping enough that it too can get excessivley hot.

In 100+ degrees temps the tires on my 35 foot Adventurer generally run at below 120 degrees with 135 being about the max I have seen. 165 would cause me some concern however I am running 16 ply tires which will run cooler than the 10 or 12 ply you probably have on the 32 foot coach.

I know that 16 ply is overkill but I will sacrifice ride for a bit more safety as I had a blowout when there were only 12 ply tires on the duals and 14 ply on the front so when I replaced them I bumped them up to 16 ply all around. If you don't see the ply rating on the tire it can be calculated by multiplying the letter position of the load range by 2. For example F is the sixth letter in the alphabet so 6X2=12.

Regards,

dieselclacker · 07-07-2010, 07:14 AM

Bob, you might try bumping up the cold tire pressure a bit, and see if this brings down the tire temps. I, like Neil V, would be concerned with tire temperature of 165. My coach is similar in size to yours, I run 85 psi in the rear, and 80 in the fronts. I can't recall ever checking the temps on a 104 degree day, but on a normal 85 degree day, they are usually in the 115-120 degree range, with the inside dual a few degrees hotter.

Dieselclacker

Ken-55 · 07-07-2010, 07:50 AM

Quote:

Originally Posted by DriVer

I use a Crossfire!

I had never heard of this system before this post.

Just Googled it . . . I'm intrigued!

Anyone else use it?

Always-RVing · 07-07-2010, 08:27 AM

I read that if there is greater than a 10 psi difference in the duals, you are dragging one.

Anyway, the psi dually difference should not be more than 5 psi and 10 psi (max), and ideally, they should come close to matching.

Quote:
Inflation mismatches on mated dual tires can cause tire diameters to differ, so the larger tire will drag the smaller tire. This results in rapid and irregular wear, especially on the smaller tire.
Tests conducted by Bridgestone/Firestone found that a five-psi difference created a 5/16-inch difference in tire circumference on a set of dual tires. In only one mile, this slight difference caused the smaller tire to be dragged 13 feet.
A truck that drives 100,000 miles per year would drag this tire 246 miles. This same type of situation can occur if tread depth and design on dual tires are not properly matched.

cameo23 · 07-07-2010, 08:50 AM

out of curiosity and specifically to add to my knowledge
base between my ears, how do you check tire TEMPERATURE?
My tire gauge just checks the pressure, but the temperature?
I'm curious

Always-RVing · 07-07-2010, 09:08 AM

Interesting Quote:
Ozone is the biggest natural cause of tire failure. Ozone is a gas which causes the rubber to become brittle which results in surface cracks which, over time, become wider and deeper.
Tire manufactures do not recommend any type of dressings or cleaners other than soap and water and say that keeping your tires clean is the best thing you can do to minimize ozone damage

Tire manufactures recommend replacing tires five to seven years old.

Tire manufactures do not recommend any type of dressings or cleaners other than soap and water and say that keeping your tires clean is the best thing you can do to minimize ozone damage.

If you do use tire dressings they should not contain petroleum products or alcohol.
Since high temperatures and ultraviolet light accelerate this destructive process, covering your tires when not in use will also help prolong their life.

NeilV · 07-07-2010, 07:19 PM

Quote:

Originally Posted by cameo23

out of curiosity and specifically to add to my knowledge
base between my ears, how do you check tire TEMPERATURE?
My tire gauge just checks the pressure, but the temperature?
I'm curious

I use a non-contact thermometer from Harbor Freight:

Non-Contact Pocket Thermometer

That one will do for tires however I am going to upgrade to one capable of checking brake temperatures such as this one:

Infrared Thermometer

cameo23 · 07-08-2010, 07:07 PM

oh, thank you, I've got a thermometer like that one,
so guess now I have another use for it.

Bob King · 07-08-2010, 11:13 PM

Cameo23; I'm using a non-contact infrared thermometer and holding at about 3 inches from the tire surface. This reading is sidewall, not tread temp. The further the gauge is from the tire, the lower the reading.
Also, I have no idea how accurate the temp gauge is, and haven't tried to calibrate it in any way. I think I will try to get a contact reading with a good thermometer and compare the results.By the way, the tire pressures are all within 1 psi using a digital pressure gauge that is supposed to be accurate to .5 psi.
Thanks to all for the replies.
Bob

JimM68 · 07-11-2010, 12:55 PM

I use a crafstman non contact IR gauge. It is very accurate, and distance doesn't effect it. I use it to read lots of things, including exhaust manifold temps to check cylinder to cylinder balance.

My tires are the same size as the OP's, 245-70-19.5 (or is it 75" i dunno, it's the same)

165 is gawdawful HOT HOT HOT, you are risking multiple blowouts!
I'd guess due to not enough air pressure.

My Toyos are marked on the sidewall max load at max pressure 120psi cold.
I'd been running them at 100, as that's where the chart wanted at my wieght.
At 100 psi, carrying about 3500 lbs per tire, I had 138 deggrees on the front tires, and 128 on the rears, checking the tread temp, in the middle, at about 3 inches.

I've since up'd the pressure to max, the rig was fighting me something awful, needing constant steering corrections, and not responding crisply to steering inputs.

At 120 psi, she is a lot happier, as am I. Next time we hit the road, in 2 days, I'll shoot hot temps again.

edit after rereading the original post, I though it worth adding that my pressure changes less than 10 psi cold to hot.

Tireman9 · 07-24-2010, 06:05 PM

Quote:

Originally Posted by Bob King

This regards Tire temps and pressure s.
I have a 2005 Hurricane 32R. The tires are 245/70/19.5Rn I run the tires at about 78 lbs cold. The other day, July 1st, I stopped at a rest area on I-40 West of Needles, CA and while there checked the tire temps. They ranged from 152 to 165 degrees F. The inner duals were the hottest. The Outside air temp was 104 Degrees. I have no idea what is normal, and did nothing about it. Out of curiosity, I checked the pressures and they were all in the 95 to 98 lbs area. Next morning, the temps were normal as was the pressure. I do know that pressure goes up with temp., but again have no idea how much.
Anyone have any thoughts or suggestions?
Thanks
Bob

Well Bob, what is missing is the information of real load on each corner of your unit. Without knowing that there is no way to know what the minimum inflation requirement is.
BUT those surface temperatures sound very high to me and along with the 20 psi gain there is some indication that 78 cold is not enough.

When you respond with the load info could you clarify the tire size.
I believe you mean a 245/70R19.5
Also what is the Load Range marked on the tires?

Bob King · 07-25-2010, 01:01 PM

Tireman9:
You're correct, the tires are 245/70R/19.5 load range F Goodyear G670. The corner weights, last time I weight it were
LF 2860, RF 2900, LR 4920, RR 6400? Steer Axel 5760, Drivers 11320. They only weighed right side, left sides are total - right side. I questioned the LR weight at 4920 but they didn't have time to re-weigh it. According to Goodyear weight tables, the tires are rated at 75# for 3740 single and 3515 dual so the pressures should be OK to slightly high. I don't know what the road temp was, but ambient air was 105 and tire temps were read after about 2 hours at 65 miles per hour. I will check the corner weights again as soon as I can find a scale.