New to towing-tire psi question (and more)

[VRMHW-M]

I have michelin m/s tires on my tahoe-they are a size larger than standard. If you need more size info i will have to go out and look at them. The psi is 35 cold. Max psi is 80. I was told that when towing our camper i should increase the psi to 50 to reduce sway. We do have a sway bar. Admittedly, i am a bit of a girlie girl and am just learning this stuff. So, since i have been given great info from my other posts here i am hoping for more of the same now.
What psi should i tow with?
What recommendations do you have regarding the sensors that go in the trailer/tv tires? I have been reading about them on other posts here, but i am not sure i fully understand.
I have also been reading a lot about swapping tires for better ones-thoughts on that? It came with radial tires but i didnt recognize the brand.
We will be traveling with precious cargo (our kids) so want to take whatever precautions necessary. Our trailer is a 2013 surveyor sv-291.
I appreciate any input and hand holding through my learning process.
Vicki

[Rockinwood]

I put ours Max 65 psi to 60 psi you dont want the underinflated esp with a load

[Rockinwood]

So, if I were you, I would put 65

[Herk7769]

<sigh>

I hope I do not once again ignite a fire storm. Forgive me.

You must weigh your suburban and camper 3 times to answer your question. Drive to your local CAT scale (www.catscale.com) and drop the camper in the yard.

Weigh the suburban "ready for caming" with your WD hitch installed, folks in their places, dog and any camping stuff normally carried inside the suburban in its place and a full tank of gas.

Record the total weight and the weight on each axle.

Drive over to the camper and hook up but leave the WD bars disconnected from the camper.

Record the total weight; the weight on the front axle, the weight on the rear axle, and the weight of the camper's axles.

Get out and hook up the bars and ask the attendent for another weigh.

Record the total weight; the weight on the front axle, the weight on the rear axle, and the weight of the camper's axles.

Inflate ALL four of the tires of the suburban to the PSI that corresponds to the heaviest loaded tire using the following inflation chart or better yet the one from your tire's manufacturer.

Inflate the camper's tires to the maximum on the tire if OEM or to the PSI required for the heaviest camper tire from the correct manufacturer's ST chart.

http://www.classbforum.com/phpBB2/vi...php?f=9&t=2158


You will get lots of other good information besides proper inflation PSI from this little exercise.

[B47]

Originally Posted by VRMHW-M

I have michelin m/s tires on my tahoe-they are a size larger than standard. If you need more size info i will have to go out and look at them. The psi is 35 cold. Max psi is 80. I was told that when towing our camper i should increase the psi to 50 to reduce sway. We do have a sway bar. Admittedly, i am a bit of a girlie girl and am just learning this stuff. So, since i have been given great info from my other posts here i am hoping for more of the same now.
What psi should i tow with?
What recommendations do you have regarding the sensors that go in the trailer/tv tires? I have been reading about them on other posts here, but i am not sure i fully understand.
I have also been reading a lot about swapping tires for better ones-thoughts on that? It came with radial tires but i didnt recognize the brand.
We will be traveling with precious cargo (our kids) so want to take whatever precautions necessary. Our trailer is a 2013 surveyor sv-291.
I appreciate any input and hand holding through my learning process.
Vicki

Wow - those are several questions and I cannot answer them all, but regarding your question about installing sensors -

I assume you are speaking about the sensors that are part of a Tire Pressure Monitioring System (TPMS). If so, then the correct way to install them is to carefully (maybe more than once)read the instructions that come with the brand you have either brough or will buy.

I believe that all of the TPMS you have read here all operate basically the same way.

The sensors that screw on to the trailer tire valve stems need to have have fresh batteries (usually supplied by the TPMS manufacturer) installed before they are installed on the stems - the instrustion manual will show you how to do this.

After the sensors are installed, each one needs to be programmed into the monitor that comes with your TPMS. The monitor is the unit that provides you with the condition of each tire - condition being the tire psi and temperature. You will need to program the monitor with the position of each sensor as they are installed on the tires, e.g. left front, right rear, etc.. The monitor is carried in your TV.

The monitor will send you a warning when and if a tire psi exceeds the "baseline" psi that you programmed into the TPMS during the programming. Baseline psi is usally the cold psi recommended by the tire manufacturer. The TPMS that I have will send an alarm when the tire psi reachs a value set into it by the manufacturer.

After programming the sensors and understanding what the various monitor readings are telling you, it should be fairly simple to use your TPMS.

IMO a TPMS is a good investment. Once again, I have only given you the basics here and suggest that you read and follow the TPMS manufacters manual.

[donn]

Yes. And I would seriously consider junking the Chinese tires under the trailer and get a set of Maxxis tires. Also you might ask the dealer what the max pressure the wheels can handle.

[SCOC]

Herk's method is solid. But let's face it, you still have to get the rig to a scale, and you might not be able to get to a scale right away, right? I'm guessing that the % of campers who've been to a scale ever is fairly low - not that that is an excuse not to go. I'm one of the few I suppose that have weighed my rig (and I haven't done it 3 times either, although I would have liked to, but soon, anyway....)

What I would do, is inflate the TV tires according to Herk's method assuming that your Rear Axle will be fully loaded. In your case, I believe that's 4200lbs but look at your sticker inside the driver's door to make sure. Do not exceed the maximum psi specified on the tire, or rim.
Inflate the trailer tires to the cold max specified on the tire, and make sure the rim can handle that pressure. This is likely 50 or 60psi, but check the tires.

My feeling is that most tire blow outs are casued by underinflation and overloading. just make sure they aren't underinflated, check the pressure often (before each tow) and you should enjoy many happy trips.

Then get to a scale when it's convienient, and adjust if required.

[Glenn5995]

Hi Vicki,

Lou has given great information on how to get the correct pressure for your tires. In case you (and others viewing this thread) don't understand the effect of tire pressure and why it is important I'll try to explain it and then give some approximate numbers for you to start with until you can weigh everything, if you decide to do that (most don't).

An over inflated tire causes the tire to ride on the center of the tread, an under inflated tire on the outside of the tread as pictured:



An underinflated tire can't maintain its shape and becomes flatter than intended while in contact with the road and could lead to tire failure. The tire’s tread life is reduced. Lower inflation pressure will allow the tire to deflect (bend) more as it rolls. This will build up internal heat, increase rolling resistance and cause a reduction in fuel economy, but more importantly is one of the leading causes of blow outs and tire failures. You will experience a significant loss of steering precision and cornering stability.

An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. An over inflated tire can be be damaged more easily when running over potholes or debris in the road. Higher inflated tires cannot isolate road irregularities well, causing them to ride harsher and tend to "bounce" over road irregularities and at times not be in contact with the road surface. Like the under inflated tire, the tire's tread life is reduced. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point.

Both under and over inflated tires have a decreased contact with the road surface, resulting in a decrease in handling and braking performance on wet surfaces.

In your case you have changed tire size and load range, so the sticker on the door for tire pressures means nothing now. The weight of your vehicle will be dependent upon options and if your Tahoe is four wheel drive or not and what cargo you will carry. A base Tahoe has a curb weight of around 5600 with around 2900 on the front axle and 2700 on the rear. The SV-291 has a dry tongue weight of 544 and dry weight of 4807 with a GWR of 7544. Lets assume you don't overload the trailer and have a trailer weight of around 7300 with a tongue weight of around 850. That would give you a weight of 6450 on the trailer tires or about 1612 per tire if the weight was equally divided between the tires (which it never is). I would therefore make sure you have enough pressure for your specific tires on the trailer to support 2000 pounds each.

Your Tahoe will now have its 5600 plus the 850 from the tongue weight of the trailer for 6450. You now have to add the weight of passengers and cargo, so let's say your Tahoe is at about 7300, which is about the GVWR for a Tahoe. You are of course using a weight distributing hitch , so the weight is fairly equal, being slightly heavier in the rear with 3500 on the front axle and 3800 on the rear axle. So the front tires would have 1750 per tire and the rear tires 1900 per tire.

When you weigh (if you do), you will probably find like most, that you are over on just about everything, so I would start with this info as a guide, make your calculations and then add 10 PSI per tire as long as you don't go over the max PSI rating for the tires. Hope this helps with at least finding a starting place, but to get it right you need to go to the scales like Lou said.

Good luck and Happy Camping!

[SCOC]

So your estimates are pretty close to just using the max axle ratings, and obviously you won't know for sure until you get it weighed.

But what's safer (without knowing actual weights)?
1) Assuming you are fully loaded at at all your max axle weights, maybe even a bit higher, meaning your tires may be slightly overinflated
2) performing an estimate which in reality is low, resulting in slightly underinflated tires.

My thoughts are that slightly overinflated tires are safer than slightly underinflated tires. So why not assume you're at the max until it's weighed? But I'd like to hear what other's think about #1 & 2 above

[Herk7769]

IMO, You are right, If you have no clue as to what "correct" is then slightly overinflated is "better" than slightly under inflated.

Slightly is the operative word since over hard tires can make for an unsafe ride as well.

When I forget to reset my truck's tires back to "normal-not towing" it is a skittish as a young girl.

I have nearly lost control on more than one occasion braking going down a hill. Trucks tear up the asphalt leaving "ripples" in the pavement at the stop sign at the bottom and when my tires are at 80PSI the truck dances all over the place. Set normally (65 PSI) they handle it just fine.

[Glenn5995]

I agree, slightly over inflated (but not over tire's max) is better. My example was just to show the "why" of the "assumptions". In this case VRMHW-W will probably be close to the capacities of both tow vehicle and trailer, but that may not be always the case. A 350/3500 pulling a pop up or hybrid would not be anywhere near capacity or a fifth wheel with a 4000 cargo capacity that someone is just throwing in a "few things" for a local weekend trip might not be as well. I just remember things better if I understand the "why" part of them.

Without knowing for sure, that is why I suggested at the end to add 10 PSI to where you think you should be - better to be slightly over than under inflated.

[Glenn5995]

Of course another method is to draw a chalk line across the tread and drive a few revolutions and check. If the chalk wears off in the center of the tread first, the tire is over inflated and you need to let air out. If the chalk wears off on the outside first, the tire is under inflated and you need to add air. Once it wears off evenly, you are about right.

However you need to drive straight for this to be accurate, especially with trailer tires. When you turn, a trailer with tandem and triple axles drag the tires sideways and will remove the chalk and not give a correct interpretation.

[Glenn5995]

Originally Posted by herk7769

IMO, You are right, If you have no clue as to what "correct" is then slightly overinflated is "better" than slightly under inflated.

Slightly is the operative word since over hard tires can make for an unsafe ride as well.

When I forget to reset my truck's tires back to "normal-not towing" it is a skittish as a young girl.

I have nearly lost control on more than one occasion braking going down a hill. Trucks tear up the asphalt leaving "ripples" in the pavement at the stop sign at the bottom and when my tires are at 80PSI the truck dances all over the place. Set normally (65 PSI) they handle it just fine.

Exactly the point, after I unhitch the fifth wheel, if I don't air back down the tires on the Power Wagon, besides loosing a kidney from the ride, it is bouncing all over the place. Can't hardly control it much over 10 MPH on a washboard dirt road.

My employer provided work vehicle is a Ford F-150 that they have put LT load range E tires on. Every time it goes in for service they air the tires up to 80 PSI and I can't hardly keep it in a lane when I hit a bump or pot hole. Going over railroad tracks usually puts my head through the roof of the cab, so I air back down to a reasonable pressure until it goes back in for service and we start the process over.

[SCOC]

Originally Posted by Glenn5995

A 350/3500 pulling a pop up or hybrid would not be anywhere near capacity or a fifth wheel with a 4000 cargo capacity that someone is just throwing in a "few things" for a local weekend trip might not be as well.

Yeah, no kidding. If someone has a 350 pulling a pop up and is concerned with adjusting their pressures between towing/not towing they got too much time on their hands. you might as well winch it up into the bed. OK, OK, I know there's some big PUPs out there, but you know what I mean....

I also assume we're not dealing with the other extreme like a minivan or RAV4 pulling a 35 footer TT either

[Glenn5995]

In the case of the OP, although she will most likely be near rated capacity for a Tahoe's GVWR and GAWR, she said the max tire pressure is 80 PSI, so she must have LT load range E tires. They have more capacity than the axles or the projected load, so she will not need them at 80 PSI.

[FreedomTracker]

OK... I guess I'm still learning as I didn't realize that tires should be inflated higher than what the TV door sticker recommends.

I have a F150 SCREW with Goodyear Wrangler SR-A tires (P275 65R18).

TOTAL RIG CAT WT.
Steer Axle: 3400 (w/ 2 passengers)
Drive Axle: 3260
TT Axle (2): 3660

CAT Wt of F150 alone w/ 1 passenger was 5900 lbs

Ford says 35lbs PSI and tire shows 44lbs PSI max. Goodyear max load chart says 2601@51. My unhitched TV by itself is 1475 lbs per tire so I'm OK on load. I called one dealer and inquired as to pressure when towing and he suggested 40 PSI which is an increase of 5 lbs PSI. Another dealer suggested 50 PSI which is an increase of 15 PSI vs. normal.

Which PSI sounds correct for towing?

[Herk7769]

Originally Posted by FreedomTracker

OK... I guess I'm still learning as I didn't realize that tires should be inflated higher than what the TV door sticker recommends.

The door sticker has the recommended pressure for RIDE not necessarily load bearing. The tire pressure MAY need to be increased up to the maximum stated on the tire in order to carry the load required of them.

[Herk7769]

Originally Posted by FreedomTracker

OK... I guess I'm still learning as I didn't realize that tires should be inflated higher than what the TV door sticker recommends.

I have a F150 SCREW with Goodyear Wrangler SR-A tires (P275 65R18).

TOTAL RIG CAT WT.
Steer Axle: 3400 (w/ 2 passengers)
Drive Axle: 3260
TT Axle (2): 3660

CAT Wt of F150 alone w/ 1 passenger was 5900 lbs

Ford says 35lbs PSI and tire shows 44lbs PSI max. Goodyear max load chart says 2601@51. My unhitched TV by itself is 1475 lbs per tire so I'm OK on load. I called one dealer and inquired as to pressure when towing and he suggested 40 PSI which is an increase of 5 lbs PSI. Another dealer suggested 50 PSI which is an increase of 15 PSI vs. normal.

Which PSI sounds correct for towing?

Part of your problem is your tires. Your tires have a P rating which is a "SL" (or standard load) metric type SUV tire and not a true Light Truck "LT" tire.

Tire Tech Information - Load Range/Ply Rating Identification

Explains why you should consider replacing your OEM tires with true truck tires if you tow. Most F-150 trucks sold never see a trailer; ever.

http://www.tirerack.com/tires/tirete....jsp?techid=70

If you insist on keeping those tires and towing, I would increase the pressure to 44 PSI whenever I was going to tow.

[Glenn5995]

As long as you have the OEM tires, you should go by the door sticker for a guide. It is when you replace tires with other than OEM that it does not apply. At what weight is the 35 PSI recommendation? I doubt it is for the GVWR. It is most likely for an empty or light load.

[Herk7769]

Originally Posted by Glenn5995

As long as you have the OEM tires, you should go by the door sticker for a guide. It is when you replace tires with other than OEM that it does not apply. At what weight is the 35 PSI recommendation? I doubt it is for the GVWR. It is most likely for an empty or light load.

Again it is for optimum ride and handling; not maximum load bearing.

http://www.4wheelparts.com/tire-whee...e-checker.aspx