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Old 01-05-2009, 10:02 PM   #1
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Towing Speed Questions

Please reference this post when answering this question:
gafishman/travel trailer fishtailing..... posted on 01-02-09
After reading the post from the aforementioned poster (gafishman) on 01-02-09 I have some questions in regards to my tow speeds.
I am towing with a 01 Chev Z71 with a 5.3 litre and full tow package. My setup is with a friction anti sway bar and equalizer hitch. . I am towing a 2009 SV291 (30 feet with tongue) with a weight in the 5,500 pound range as towed.
I have read posters who said the safe towing speed for this set-up is 60 mph. I have pulled this set-up before (when first bought, two times) with a 2004 Expedition with much sidesway (after being passed by semis) on the interstate. After buying a Z71 and pulling the SV291 with said 2001 Z71 I have not had any, AND I REPEAT, ANY, sidesway problems. Which leads me to this question. Since I am new to the heavier weight towing conditions (having traded a pop-up for the SV291) I am wondering about tow speeds. We have put about 2,000 miles on the TT and have not had any problems.
The data on the tires reads this way:
Good Year Marathon (made in China)
ST 205-75 R 14
Load Range C
4 Ply
2 X poly
2 X Steel
(Sidewall = 2 poly cord)

I tow at 60 to 70 mph. Is 65 a good median speed?
Thanks for any responce.
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Old 01-05-2009, 10:55 PM   #2
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ST tires are rated for 65 mph max.
I travel 65 mph, max, on Interstate and 50-60 on state highways.

Quote from tire web site:
A load range C tire is at its peak load capacity(1760 lbs. ea) when inflated to its maximum pressure of 50 psi.

All ST tires have a maximum speed rating of 65 MPH. Drive faster than that and risk tire failure. That’s because as heat builds up the tire's structure starts to disintegrate and weaken. The load carrying capacity gradually decreases as the heat and stresses generated by higher speed increases. Plan enough time to get there without a tire mishap.
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Old 01-06-2009, 06:36 AM   #3
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I think the important thing is, we need to slow down and plan to leave a little earlier and to use common sence. Some people do not realize how weight reacts while towing and the devastation they can cause and the possibility of the loss of life if something screws up either mechanical or human error. The number 1 cause of accidents is speed, going too fast. The other thing is improper towing equipment like hitches and the biggest thing I see on the road is an improper TOW VEHICALES. If a law was past across the U.S. in order to tow a camper one would have to pass a drivers test most people would not get a licence to do so based on what is on the road to day. And as far as hitch work, I think a Certification is in order for those who do this kind of work for a living. Some one needs to be held accountable. Not all people are mechanically inclined an depend on the dealer ship to make sure all equipment used is correct and the proper tow vehicle is being used along with the proper installation. I have experienced myself, a dealer will tell you anything the make a sale, safety is not on there mind just the $$$$$$. This is my opinion and please do not take it personnel. There people that do the right thing, but the people that do not know any better have to rely on others to do the right job.
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Old 01-06-2009, 09:16 AM   #4
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Since you asked the question I'm going to elaborate on a few more things. I hope you don't mind.

Quote:
Originally Posted by Bill U View Post
I have some questions in regards to my tow speeds...
I tow at 60 to 70 mph. Is 65 a good median speed?
Yes 65 is a good speed. Since the tires are rated for 65 I wouldn't suggest staying above that for very many miles at a time.

Quote:
Originally Posted by Bill U View Post
I am towing with a 01 Chev Z71 with a 5.3 litre and full tow package. My setup is with a friction anti sway bar and equalizer hitch. . I am towing a 2009 SV291 (30 feet with tongue) with a weight in the 5,500 pound range as towed. I have read posters who said the safe towing speed for this set-up is 60 mph. I have pulled this set-up before (when first bought, two times) with a 2004 Expedition with much sidesway (after being passed by semis) on the interstate. After buying a Z71 and pulling the SV291 with said 2001 Z71 I have not had any, AND I REPEAT, ANY, sidesway problems.
I'm glad you got a more stable TV. My guess is that the Z71 has LT designated tires on it and the Expy had P rated tires. The Z71 also has a bit stiffer suspension. Those things are why you're not getting any sway.

NOTE: Friction sway bars aren't recommended for anything over 26' and if you do use them you need two(2) of them. Your WD (Weight Distribution) hitch doesn't do anything for sway.

With a 30' long RV I'd suggest you get a WD with built in sway control such as the Reese Dual Cam or the Equal-i-zer (not to be confused with equalizer). Or at the very least add the dual cam to your existing WD hitch. AND make sure it's set up correctly.

I also recommend getting a good brake controller and making sure all your brakes are working properly.

Final Thought: Sway control should not be the fix for a bad setup. Sway control should be added as insurance against abnormal conditions (i.e. passing a semi, cross winds, semi passing you, tire blowout, etc.)

Sorry for being so long but I believe this needs to be repeated often.
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Old 01-09-2009, 10:27 AM   #5
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We tow our 33 ft with any problems because of the Equl-i-zer hitch. Like milzat, I tow no more that 65 in intersate. I try to stay 60 to help stay in overdrive. (Yes I can drive in overdrive because of the computer tune and extra tranny cooler).

I think you are doing better with Z71 because it has a longer wheelbase.

David
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Old 01-09-2009, 11:46 AM   #6
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Yup, I'd dump the friction bar for something more substantial as suggested by other posters. It's always the exception and a cascading of unusual events that gets people into trouble. That's what you need to be prepared for.
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Old 01-21-2009, 09:42 AM   #7
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My preference is 60 mph secondary highways - 65 Interstates. It gives me the best control and fuel milage. The Durango handles the TH with ease and sway, even on the Interstates, is seldom a problem.
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Old 01-21-2009, 10:40 AM   #8
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From Goodyear Website about Speed Rating on "Marathon ST" tires:

Industry standards dictate that tires with the ST designation are speed restricted to 65 MPH under normal inflation and load conditions unless a different speed restriction is indicated on the sidewall of the tire.
· Based on industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph, it is necessary to increase the cold inflation pressures by 10 psi above the recommended pressure for the load.
o Do not exceed the maximum pressure for the wheel.
o If the maximum pressure for the wheel prohibits the increase of air pressure, then the maximum speed must be restricted to 65 mph.
o The cold inflation pressure must not exceed 10 psi beyond the inflation specified for the maximum load of the tire.

Now we have maximum tire pressure, and don't forget to check those fancy wheels because some of those have a low maximum pressure. And don't forget about your valve stems, which no one has mentioned. The all rubber valve stems are rated at 45 psi, in most instances. (They will stand 60 psi under most instances). Hi Pressure stems, usually have a metal barrel with a rubber
mounting, are rated at 80 psi usually. Bolt in stems are rated over 100 psi, for those with Motor Homes. If your valve stems have been recalled, I would suggest replacing them with a hi pressure stem. It won't hurt even at the lower pressures.

Hope this helps instead of adds to the discussion.
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Old 01-21-2009, 04:33 PM   #9
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Thanks for the info.
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Old 01-21-2009, 07:00 PM   #10
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Question? where is the dividing line between low and high pressure. I have a 3/4 ton Suburban that has 10 ply tires on it and max inflation rate is 80 psi and the valve stems are all black rubber and they are high pressure rated. I also have a Chevy Trail Blazer that have metal jacket valve stems but the max inflation rate on the tires are 32 psi and this is from the factory.
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Old 01-21-2009, 08:47 PM   #11
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Sixty tops to be safe. Drove 3000 miles last year in 2 weeks and never went over 60 interstate or not. I feel much safer and am sure those around me do as well. What's the rush? You'll only be getting to your funeral that much faster. Best fuel mileage can be had below 60 as well. This 65 tire rating is the max. Why does everyone think they have to go that speed. Just because your tachometer redlines at 7000rpm does not mean you run your engine at 7000 every chance you get......................................
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Old 01-21-2009, 10:11 PM   #12
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Tire and valve stem pressures

I apologize for any confusion about valve stems, so let me try to clear this up. I am an ASE certified Master Technician, and I have seen many tires mounted with wrong valve stems. It seems that after you learn to sweep the shop, your next job is to mount tires. The dividing line between low and high pressure is around 50 psi, then again at 90~10 psi. Regular valve stems are all rubber, but may have a metal sleeve over them for decoration. High pressure stems will have an all metal barrel, usually brass colored, with the only rubber being down near the wheel. Very high pressure stems will have a nut and washer, and a sealing washer down near the base of the valve stem. Rockwood06, if you have changed tires on your truck, and they gave you new valve stems, I would be concerned.

One last bit of info. Check tire with the proper gauge. Tire gauges are routinely only accurate in the center of their range. A 100 psi gauge will read 50 psi to within 1%. BUT at the edges, it get sloppy. AT 90 psi, the same gauge is only 10% accurate. SO, if your car tires need 30 psi, use a gauge that has a maximum of 50~60. If your trailer tires need 50 psi, you need a 100 psi gauge, and for 80 psi tires, you need a 150 psi gauge. And this is why mechanics go broke buying tools trying to do the job right.

Just remember, mounting tires is like installing WD hitches, there's no test to pass, and as long as it holds air till you get off the lot, who cares?

Sorry to be so long, but your tires are all you have between you and the road, and tires cause more problems than many realize.

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Old 01-21-2009, 11:15 PM   #13
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Once again, thanks for the good info. I know it will go a long way.
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Old 01-21-2009, 11:31 PM   #14
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Would it be safe to say that when mounting new tires, no matter what the rating, to use high pressure valve stems?
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Old 01-22-2009, 05:56 AM   #15
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Quote:
Originally Posted by windrider View Post
I apologize for any confusion about valve stems, so let me try to clear this up. I am an ASE certified Master Technician, and I have seen many tires mounted with wrong valve stems. It seems that after you learn to sweep the shop, your next job is to mount tires. The dividing line between low and high pressure is around 50 psi, then again at 90~10 psi. Regular valve stems are all rubber, but may have a metal sleeve over them for decoration. High pressure stems will have an all metal barrel, usually brass colored, with the only rubber being down near the wheel. Very high pressure stems will have a nut and washer, and a sealing washer down near the base of the valve stem. Rockwood06, if you have changed tires on your truck, and they gave you new valve stems, I would be concerned.

One last bit of info. Check tire with the proper gauge. Tire gauges are routinely only accurate in the center of their range. A 100 psi gauge will read 50 psi to within 1%. BUT at the edges, it get sloppy. AT 90 psi, the same gauge is only 10% accurate. SO, if your car tires need 30 psi, use a gauge that has a maximum of 50~60. If your trailer tires need 50 psi, you need a 100 psi gauge, and for 80 psi tires, you need a 150 psi gauge. And this is why mechanics go broke buying tools trying to do the job right.

Just remember, mounting tires is like installing WD hitches, there's no test to pass, and as long as it holds air till you get off the lot, who cares?

Sorry to be so long, but your tires are all you have between you and the road, and tires cause more problems than many realize.

Windrider

Excellent information, thanks a lot. There is a price to pay for not taking the time to investigate. As far as the tires that were changed out on the Suburban, I have been dealing with the same people for almost 30 years and when the tires were changed out the high pressure valve stems were ordered, so I am confident with my Mechanic. The valve stems on the Trial Blazer are those type that you mentioned, they are short and look like there is a nut and washer at the face of the rim, but why would this type of set up be on a Trail Blazer, It's a 2007? because the max pressure rating on the tires are 32 psi. this makes it a low pressure tire if 50 psi is the cut off.
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Old 01-22-2009, 09:33 AM   #16
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Rockwood06, Can't explain the valve stems on the Blazer from memory, but it probably has something to do with the design of the wheel. If you have fancy aluminum wheels, they have to be thicker than steel, and that thickness may not let a conventional valve stem work. The thickness may require a clamp-in type valve stem. Amost the same thing with wheel weights. In the old days, when you balanced a tire you put on wheel weights, one size fits all. Today there are over 5 styles of wheel weights in use, not counting some very specific weights designed for one wheel only, which nobody carries, not even the dealer, hence, stick on weights to the rescue. I would suggest on the Blazer when it'e time for tires, you check a couple of days in advance, and ask about replacing those valve stems. Give the shop a chance to find the correct ones.

Another warning. Don't let age of a shop fool you into thinking they they know what they're doing. I went into a shop, and was making a guy remount a set a tires because of the wrong pressure valve stems. The owner for 15 years had a fit, never heard of search a thing. Called the parts house and ordered all three kind in a package with specs printed on it, (very expensive way to buy), in order to prove my point. There is a "sticky" note posted about tires and valve stems for futher reading if you desire. Thanks for letting me have the soapbox once again.

Windrider

To Bill U, yes, for the most part it would be safe to mount use high pressure valve stems when mounting tire. They will leak a litle under low pressure, so check pressure more regularly, say, twice a month instead of once. Also don't forget to check them during time of temperature change. Ten degrees of air temp equals one pound of pressure, as a rule of thumb.
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Old 01-22-2009, 01:34 PM   #17
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Quote:
Originally Posted by windrider View Post
Rockwood06, Can't explain the valve stems on the Blazer from memory, but it probably has something to do with the design of the wheel. If you have fancy aluminum wheels, they have to be thicker than steel, and that thickness may not let a conventional valve stem work. The thickness may require a clamp-in type valve stem. Amost the same thing with wheel weights. In the old days, when you balanced a tire you put on wheel weights, one size fits all. Today there are over 5 styles of wheel weights in use, not counting some very specific weights designed for one wheel only, which nobody carries, not even the dealer, hence, stick on weights to the rescue. I would suggest on the Blazer when it'e time for tires, you check a couple of days in advance, and ask about replacing those valve stems. Give the shop a chance to find the correct ones.

Another warning. Don't let age of a shop fool you into thinking they they know what they're doing. I went into a shop, and was making a guy remount a set a tires because of the wrong pressure valve stems. The owner for 15 years had a fit, never heard of search a thing. Called the parts house and ordered all three kind in a package with specs printed on it, (very expensive way to buy), in order to prove my point. There is a "sticky" note posted about tires and valve stems for futher reading if you desire. Thanks for letting me have the soapbox once again.

Windrider

To Bill U, yes, for the most part it would be safe to mount use high pressure valve stems when mounting tire. They will leak a litle under low pressure, so check pressure more regularly, say, twice a month instead of once. Also don't forget to check them during time of temperature change. Ten degrees of air temp equals one pound of pressure, as a rule of thumb.




Now you have brought up another issue I have to consider, Not too long ago I posted an issue I had with the receiver that came with my new truck, It is under "What's the differents between Receivers" It was recomended to change the tires out from a 4 ply tire to a 10 ply tire by the dealer, now I will have to see if the aluminum wheels that came with the truck are rated for an 80 psi tire and that means that the valve stems would have to be changed. Here I go back to to the dealer again. The info that you have supplied has open my eyes even more.
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Old 04-12-2009, 11:14 AM   #18
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With properly inflated tires in good shape on both the truck and trailer you should be able to maintain highway posted limits. Remember that you may have to stop quickly in an emergency due to some fool cutting you off or pulling some bonehead maneuver in front of you. Once your trailer decides to go out of control "jackknifing" you may not be able to correct quick enough. Drive at your own comfort levels. It's better to get to the campground than a tow yard.
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