Uniroyal Tires

Topic: Uniroyal Tires (Read 3628 times) previous topic - next topic

Re: Uniroyal Tires

Reply #50 – January 24, 2018, 05:56:50 pm

Quote from: jcus – January 24, 2018, 05:50:04 pm

What does 120 as the UniRoyal recommended mean?

It might mean they figure the DW collects rocks at each stop? $:-\$

Re: Uniroyal Tires

Reply #51 – January 24, 2018, 05:58:22 pm

120lbs pressure

Re: Uniroyal Tires

Reply #52 – January 24, 2018, 06:02:51 pm

Quote from: mike leary – January 24, 2018, 05:56:50 pm

It might mean they figure the DW collects rocks at each stop? $:-\$

Lot of rocks, 120 psi will support 37240 lbs. Mike is that your coach at the side of a house in Ajo?

Re: Uniroyal Tires

Reply #53 – January 24, 2018, 06:17:49 pm

Quote from: jcus – January 24, 2018, 05:50:04 pm

What does 120 as the UniRoyal recommended mean?

On the side of the tire (if you have good glasses on) will be information in small print as to the capacity in pounds and the pressure for that capacity. Since the maximum pressure is also the maximum load the tire will carry, it's probably what he meant.

Go under the coach with someone at the wheel rocking it back and forth. Check for worn tie rod ends, other suspension/steering components. That could be causing the problem. Good to have strong flashlight as the wear may be hard to see. Did you have any shimmy before the new tires?

As the rotor wears towards minimum thickness, it may distort when it becomes hot and can give a little shimmy when the brakes are applied. I just put a new set of drilled/vented rotors on our car. No runout but when they get hot, it develops a shimmy, bad when really hot. A lesson in aftermarket rotors.

Pierce

Re: Uniroyal Tires

Reply #54 – January 24, 2018, 06:23:38 pm

Quote from: jcus – January 24, 2018, 06:02:51 pm

Is that your coach at the side of a house in Ajo?

No, we're at Shadow Ridge RV Resort. The GV belongs to a friend, has not run for years, sad story. I inspected it last year, also sad.

Re: Uniroyal Tires

Reply #55 – January 24, 2018, 06:28:37 pm

Quote from: Hans&Marjet – January 24, 2018, 05:58:22 pm

120lbs pressure

I am confused, is the chart you posted not the UniRoyal recommend pressures for your weight?
I thought you wanted help in determining the right pressures.

Re: Uniroyal Tires

Reply #56 – January 24, 2018, 07:12:12 pm

Hans & Marjet,
The tire pressure chart I previously posted came directly from Uniroyal technical support. I questioned them about the axle weight chart and was advised that it was not recommended for RV's. Corner weights can be achieved on a truck scale with a little ingenuity.

How to Weigh Your RV

Bob

Re: Uniroyal Tires

Reply #57 – January 24, 2018, 08:17:23 pm

Quote from: Hans&Marjet – January 24, 2018, 05:46:40 pm

So....Yesterday after the install I asked the guy's what pressure on the tires...response "120" as the UniRoyal" recommended.

Drove towards home.....got lost 'ANOTHER STORY"..... all felt good....but I still have a shimmy when applying the brake hard....PS
had the rotors checked for "runout" all OK....
Thoughts..

Your tire guy is wrong. He just quoted the max cold tire pressure permissible. Set pressure based on actual weight of the coach.

Re: Uniroyal Tires

Reply #58 – January 24, 2018, 08:17:37 pm

Quote from: jcus – January 24, 2018, 06:28:37 pm

I am confused, is the chart you posted not the UniRoyal recommend pressures for your weight?
I thought you wanted help in determining the right pressures.

Jim I do want the correct inflation pressures....I just quoted what the tech told me after the installation. " i set the pressure @ 120 as the tire folks recommended"

Re: Uniroyal Tires

Reply #59 – January 24, 2018, 08:23:05 pm

Quote from: Pierce & Gaylie Stewart – January 24, 2018, 06:17:49 pm

On the side of the tire (if you have good glasses on) will be information in small print as to the capacity in pounds and the pressure for that capacity. Since the maximum pressure is also the maximum load the tire will carry, it's probably what he meant.

Go under the coach with someone at the wheel rocking it back and forth. Check for worn tie rod ends, other suspension/steering components. That could be causing the problem. Good to have strong flashlight as the wear may be hard to see. Did you have any shimmy before the new tires?

As the rotor wears towards minimum thickness, it may distort when it becomes hot and can give a little shimmy when the brakes are applied. I just put a new set of drilled/vented rotors on our car. No runout but when they get hot, it develops a shimmy, bad when really hot. A lesson in aftermarket rotors.

Pierce

Pierce...Yes I did have the shimmy before the new tires...but not all the time.....if the brakes are used extensively..it does not happen.

When brakes are cold its prevelant..

H

Re: Uniroyal Tires

Reply #60 – January 24, 2018, 08:25:53 pm

That's the same trash our installer told us.

Re: Uniroyal Tires

Reply #61 – January 24, 2018, 09:28:24 pm

Your weights are a little over mine. ( I have to rescale after removing both Curb side chairs and some other stuff) MY tires are 295/75/-H LR. My table showed about 85# front and 82 Rear .
I tried 100X6 and it rode harsh . Now i run at 90X6 and it is much better. Still well over the chart values by about 6#.
Short story is run as much as you can tolerate . If you have a data port or boost gauge, put the pressures up to 105 X6, run the bus down the road about 10 miles in both directions on cruise, ( not in any draft!! ) watching the % throttle value or power level or boost value. Let the air down 10#, run it again recording the average power levels . My guess is that at about 85# you will see a couple % increase in required power or .5-1 # boost. That means that it takes more fuel to run less pressure.
Make your pressure settings based upon your priorities. Someplace between max fuel and max ride . IMHO.
Run at least the chart lower end plus 5-6# for safety .

Re: Uniroyal Tires

Reply #62 – January 25, 2018, 12:29:59 am

Quote from: Hans&Marjet – January 24, 2018, 08:23:05 pm

Pierce...Yes I did have the shimmy before the new tires...but not all the time.....if the brakes are used extensively..it does not happen.
When brakes are cold its prevelant..
H

Our Meritor brakes are unique to some motorhomes and fire trucks. I think it is possible that you have a rotor problem. Not very many shops know much about the brakes you have. I would go down to your fire department and find out where the maintenance shop/master mechanic is and then ask about your symptoms as well as asking who does their work or if it's done in house. I have the Meritor service manual with part numbers if needed.

What Mike/Protech racing says is true. But anytime you see a percent increase in required power, you also see an increase in tire temperature. High tire temperatures combined with hot weather are a recipe for failure or impact damage. Low pressure also means the tire can't support as much weight. One of the reasons I run all at 110 psi. If it effects the ride, then reduce it a little until it's passable. Our ride is fine at 110.

Pierce

Re: Uniroyal Tires

Reply #63 – January 25, 2018, 12:38:58 am

Pierce what exact tires are you running?

Normal function as far as I know is for any tire to increase its temp in use.

My car has temp/ pressure gauges on all wheels. Pressure rises ten percent in use.

Thats using the manufacturers tire pressure on the door opening.

Tried up to 10 pounds more if racing and all added about the same percentage temp

Re: Uniroyal Tires

Reply #64 – January 25, 2018, 10:26:38 am

I can see why the tech, might have said max. inflation. Many rv's, tt's, and 5th wheelers are designed without regard for side to side loading. Some units may have a water tank on one side and when filled, that side [and tire] are more heavily loaded than the other side. Or factory gives a weight without fuel, water, propane etc.
I think James T. at FOT once said every Foretravel coach was designed to have a max of 250 lb difference side to side on one axle no matter what was in the tanks, so you can basically set your tire pressures by the axle weight. Of course it is better to get 4 wheel loading, just to be sure. [Maybe DW did leave a pile of rocks in one side of a compartment].
Think UniRoyal is just CYA in case some one has a coach with 6100 lbs on one tire and 4500 on the opposite one.

Re: Uniroyal Tires

Reply #65 – January 25, 2018, 10:54:18 am

We have all Coopers except for one new Firestone. No pressure gauges or equalizers. I check every 3-4 days while on the road as well as thumping them. These have average sidewall flex/radial bulge but not as much as some. Good steering with no wandering. No tread noise.

Tires will increase temperature some on winter days and a lot in hot summer weather. All pressure specs on the side of tires are for cold inflation. Tires will take well over 300 psi without blowing out. Alcoa wants to make a very conservative max on their wheels but since they are forged, they will never fail. Even in accidents, they bend but won't break a piece off like cast aluminum. No tire pressure adjustment during the day no matter how hot it gets.

We just happened to run Coopers at the fire dept. We maxed the pressures on every piece of equipment and checked on the once a week service day. The 10.00-20s were inflated to their 100 psi max and the 11.00-20/22.5s to their max rated pressure of 110 psi. All cars, etc were to max spec pressures.

Our fire chief left his car running outside of his house for a quick stop. Someone stole it and headed through town and then north on Highway 101 at maximum speed. The city police took up the chase but every police car had massive blowouts at the high speeds. It took the CHP (with different tires) to keep up with the guy and finally stop him. A good recommendation for Coopers and having the correct pressures in the tires.

I ran four different pressures on my race car for circle tracks and different pressures for a road race course like Willow Springs. I think it was something like 17 psi front left, 35 psi FR, about 38 RR and 36 LR for tracks like Saugus. A lot depended on track temp and condition.

Our fire apparatus in responding to emergencies made maximum use of the brakes with near lockup at every red light/stop sign as well as making turns as fast as was safe. Not a place for a poor performing tire.

I can't think of a bus or trucking company that does not max out the recommended cold pressure.

While I max out the pressures on our car, the Bridgestones on the RAV4 give too hard a ride at their 55 psi max so I drop it down into the 40s. I did try a set of Coopers on the RAV and while they were very quiet and had a soft ride, they had poor turn in. Bridgestone did not have the lower profile tire I wanted so I will go back to my favorite all around tire for the RAV, the General Altimax the next time. Great handling, snow, etc and almost no noise when new. I find all tires on our AWD start to make noise after about 30K and then becoming progressively noise with more mileage.

Pierce

Re: Uniroyal Tires

Reply #66 – January 25, 2018, 12:40:40 pm

Pierce thanks for your reply. The only mention of the 10" tires goes way back.

Maybe it's time for those interested to help me do a what I thought was a valid inflation test for traction I used long ago.

We were skiers back 30 years ago and dry camped many times and drove on icy roads countless times.

My want was to not be driving on the center or conversely the edges of the tires in low traction uses.

You may all laugh with your superior knowledge thirty years later but let me tell you the test I did with literally a hundred foretravel owners including the first unihomes with the Xza pilots on them.

I would find an area where there was nice white concrete and a water puddle next to it.

Slow speed through the water then onto the concrete. Short distance. As the tires dried off the contact patch showed the evenness of the carcass pressure on the ground.

You may see where this is going. Over inflated the edges dried out first. Under the opposite.

Slight arc so you could separate the front and rear tracks.

Five pounds difference would change the patterns.

No idea if this was correct or if it still works but I did several a day sometimes with owners.

Everyone was a skeptic.

The even dry out patch matched the pressure/load calculations exactly.

You might assume the tire makers chart was arrived at with a sensored test to measure the contact pressure across the tire?

I do remember seeing something like this long ago I think.

Stands to reason as otherwise why not just inflate every tire to max. Why bother with the charts at all?

Altering the tire

Re: Uniroyal Tires

Reply #67 – January 25, 2018, 02:56:50 pm

This sheet was handy for pressures when tire sizes were changed. Sent it to Michelin and they replied with much less than 110 lbs. !

Re: Uniroyal Tires

Reply #68 – January 25, 2018, 06:46:34 pm

Bob,

The charts are nice in the forum world but do you think for a second that 18 wheelers change pressure as their load changes or buses change pressure as passengers get off an on?

Pierce

Re: Uniroyal Tires

Reply #69 – January 25, 2018, 06:56:30 pm

So , do you run 85 all around?

Re: Uniroyal Tires

Reply #70 – January 25, 2018, 07:01:21 pm

Quote from: Pierce & Gaylie Stewart – January 25, 2018, 06:46:34 pm

The charts are nice in the forum world but do you think for a second that 18 wheelers change pressure as their load changes or buses change pressure as passengers get off an on?

True dat, they max the pressure and roll! What Michelin told me, is RVs sit from time to time, and that's the where the psi problem happens. Case in point: when we bought the coach, the PO (not Brett!) told me that he always ran 70 lbs. Seemed low to me, but being a different model tire, I believed him. WRONG! Michelin told me that 70lbs could wreck a tire if it was sitting too long. After they looked at Brett's chart they told me 85 in the bow and 80-85 in the stern. Therein is a darn good reason to know the coach weights and what the mfgr. specs!

Re: Uniroyal Tires

Reply #71 – January 25, 2018, 07:19:02 pm

Quote from: Protech Racing – January 25, 2018, 06:56:30 pm

So , do you run 85 all around?

110 all around.

P

Re: Uniroyal Tires

Reply #72 – January 25, 2018, 07:42:55 pm

This is about cars, but do not see why it does not apply to truck tires also. With busses and trucks, the driver will probably not know what his load is, or is going to be, so max inflation pressures are prudent to cover all possibilities.
With your coach, once you weigh it in travel condition, it will probably stay within a 1000 lbs of that figure unless you add some more gear or equipment. In this case, best to follow the manufacturers recommendations for best ride and traction.
Over-inflated tires are a bad idea – WHEELS.ca

Re: Uniroyal Tires

Reply #73 – January 25, 2018, 07:47:02 pm

Quote from: mike leary – January 25, 2018, 07:01:21 pm

True dat, they max the pressure and roll! What Michelin told me, is RVs sit from time to time, and that's the where the psi problem happens. Case in point: when we bought the coach, the PO (not Brett!) told me that he always ran 70 lbs. Seemed low to me, but being a different model tire, I believed him. WRONG! Michelin told me that 70lbs could wreck a tire if it was sitting too long. After they looked at Brett's chart they told me 85 in the bow and 80-85 in the stern. Therein is a darn good reason to know the coach weights and what the mfgr. specs!

Mike,

I wish I could find the PDF on storage and ultra low speed tire pressure. If a coach is close to gross weight, a large increase in tire pressure is recommended while stored or jacking the vehicle to reduce the weight carried by the tires. Heavy machinery that travels under 5 mph also has to increase pressures over the recommended maximum. Michelin also recommends replacing any tire that has lost pressure enough to collapse it. I do move the coach every couple of weeks so the tires don't sit on one spot.

The majority of tire gators you see on the highways are from retreads. Other than a piece of steel that ruined a sidewall, the U300 has gone over 40,000 miles and my bus went many more miles without any tire problems using my "keep it maxed it out" approach. We never had a problem with tires in the FD either.

Re: Uniroyal Tires

Reply #74 – January 25, 2018, 09:00:45 pm

Would you also run your car at the tire max pressure/load rating? Most auto tires have the max load at 45-50#. The car requires maybe 32 - 40 # for the designed ride,wear and road holding.
It appears that your bus tires are 15 - 20 # over optimal /design value. Is that the way you see it also?
Maybe I dont get it, but weighing the bus,and consulting the tire chart gives us a valid pressure . In the above coaches, mine included , the front load is sub 9500# and the chart says about 85- 88# for 295/75 -Hrated tires .
Also true for extended storage tires are put way up . The instructions will also state to reduce the pressure to the correct values before you drive.

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