That squishy feeling. TV tire pressure too low?

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sfelber9

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Dec 17, 2016
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Hey everyone. Just returned from our first trip. Association Island KOA, Henderson NY. I'll get to that in another post for the review.

My main question is whether or not my TV tire pressures are too low. Through years of driving and sensing the vehicle around me, I think I have a good sense of what my truck is doing underneath me. I have made the mistake of overloading a truck or two and remembered that "Squishy" side to side feeling like the tires are low on air. It didn't dawn on me until after we got home and I was talking with the friends that were camping next to us. He said it looked like it was towing ok.  We talked about how I felt that "squishy" feeling in my buttocks in the seat when driving. The topic of air pressure came up and I think that might be the verdict.

The tire pressure sensors that are built into the truck (GMC Sierra) showed me running around 39-40 psi when hauling the camper down the highway at speed.

The "cold" rating is 44psi.

Should I be at that before coupling to the trailer and traveling?

Will that "firm-up" the feeling in my "seat"?

Each time I felt it I was checking my mirror to see if the trailer was starting to sway, that's the sensation is was getting.

Could it be just the aerodynamics of the trailer behind me? 8 foot wide by 11 foot tall box on wheels. LOL.

We head back out next Friday for round 2. About an hours' drive on the NYS Thruway. Similar driving conditions as this past trip.






 
The ONLY way to KNOW what the proper tire pressure should be is to weigh each axle (perferably each corner of the vehicle) and set your tire pressure for the weight on that tire.

How long is the "box" you are towing? 

Since you don't know what your weights are I would set the tire pressure for the 44 pounds.

NOTE: You mention a squishy feeling like the trailer is swaying.  Is it possible you don't have enough weight in the front of the trailer?  Too light of hitch weight will cause the trailer to start swaying, maybe just little enough sway that you can't see the sway.

BTW the only times I have felt the squishy feeling from low tire pressure was when the pressure was so low it was very obvious the tire was going flat.
 
AStravelers said:
The ONLY way to KNOW what the proper tire pressure should be is to weigh each axle (perferably each corner of the vehicle) and set your tire pressure for the weight on that tire. THERE IS A SCALE AT THE PILOT TRUCK STOP ACROSS TOWN. SO I'LL HAVE TO FIND A DAY TO DO THAT.

How long is the "box" you are towing?  THE BOX IS 36' TIP TO TAIL.

Since you don't know what your weights are I would set the tire pressure for the 44 pounds. LET'S SEE HOW THAT GOES FOR NEXT WEEK.

NOTE: You mention a squishy feeling like the trailer is swaying.  Is it possible you don't have enough weight in the front of the trailer?  Too light of hitch weight will cause the trailer to start swaying, maybe just little enough sway that you can't see the sway. I THOUGHT I MIGHT HAVE HAD TOO MUCH WEIGHT ON THE NOSE. I HAD THE BED OF THE PICK UP HALF LOADED WITH FIRE WOOD, FOLDING CHAIRS, POP UP TENT. THE CAMPER HAD ABOUT 1/3 FRESH WATER IN THE TANK

BTW the only times I have felt the squishy feeling from low tire pressure was when the pressure was so low it was very obvious the tire was going flat. FIRST TRIP OUT, SO MAYBE JUST HAVE TO GET USED TO IT. I.M.O. I AGREE IT SHOULDN'T FEEL THAT WAY.
Click to expand...
 
I will second the Scale it.

I have heard of a "Trick" that MAY indicate but I'm not sure I woudld trust it

Put a chalk mark across the tread, Drive a SHORT distance and check the mark

Evenly worn off or all gone (Short may be just a block) GOOD
Center remains INcrease pressure and try again
Just edges remain Too much pressure

But I stress this is temporary till you can scale it.
 
If I understand this correctly, you have a truck loaded down pulling a very long trailer and the truck has passenger car tires on it.  If that is correct, you need to start at square one and re-evaluate the whole deal, it doesn't sound pretty.
 
Can you please provide a bit more info.  For the GMC truck, what year and model?  1500?  2500?  What is the truck GVWR and Payload from the yellow placard on the driver door latch post?  What tires are on the truck?  What is their max load limit?

Year, make model of trailer and the TT  GVWR?
 
grashley said:
Can you please provide a bit more info.  For the GMC truck, what year and model?  1500?  2500?  What is the truck GVWR and Payload from the yellow placard on the driver door latch post?  What tires are on the truck?  What is their max load limit?

Year, make model of trailer and the TT  GVWR?
Click to expand...

I agree.

The OP is hauling a lot of trailer.
I don't believe tire pressure or tire type alone are the sole culprit.
 
grashley said:
Can you please provide a bit more info.  For the GMC truck, what year and model?  1500?  2500?  What is the truck GVWR and Payload from the yellow placard on the driver door latch post?  What tires are on the truck?  What is their max load limit?

Year, make model of trailer and the TT  GVWR?
Click to expand...

Absolutely...

2018 1500 GMC Sierra with 3.73 rear gear. WD hitch. Prime Time LaCrosse 3211RK. 7400 dry weight. 780 hitch.
 
You need to get that rig weighed. 
Sure some 10ply tires may help, but if you are overloaded or nearly overloaded with that much trailer you likely need more truck.
That is a lot trailer behind you.  I would not be surprised if that trailer is closer to 9,000 pounds (or more).  Based on the information you provided, I assume you're not aware of the more significant numbers that grashley requested.



 
NOTE: You mention a squishy feeling like the trailer is swaying.  Is it possible you don't have enough weight in the front of the trailer?  Too light of hitch weight will cause the trailer to start swaying, maybe just little enough sway that you can't see the sway. I THOUGHT I MIGHT HAVE HAD TOO MUCH WEIGHT ON THE NOSE. I HAD THE BED OF THE PICK UP HALF LOADED WITH FIRE WOOD, FOLDING CHAIRS, POP UP TENT. THE CAMPER HAD ABOUT 1/3 FRESH WATER IN THE TANK
Click to expand...
Is your trailer hitch a weight distributing hitch(WDH)?  Even if you have WDH with a 36' trailer you will have a huge amount of tongue weight and add to that a loaded bed in the p/u, you could have far too little weight on the front tires of the p/u.
 
I'm thinking that "squishy" feeling may actually have been too little weight on the front (steer) axle. He has a heavy trailer tongue weight, a heavy load in the truck bed, plus passengers and gear.  I'll bet that truck was squatting down in the rear and nose high. Lifting weight off the steer axle makes the steering "light", meaning lacking good feel or preciseness.  Plus having softer sided tires and maybe inadequate pressure in the back, which tends to make the whole rig squirm a bit.

Agree with the others - at best that 1500 is going to be loaded to the max, regardless of tires and psi. 
 
Thanks for all of your input everyone!!!

I will definitely get the rig weighed and redistribute some of the load to see if it helps with the balance.

With the WD hitch, the overall "view" of the set up wasn't the "Flying-V" we all see going down the road. But it wasn't dead-level. I've already made a list of what to move where to see what helps.

 

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Open the driver door and look for the yellow placard which states the maximum weight of all passengers and cargo shall not exceed XXXX lbs and report that back, please. 
Also, what tires does it have on it?  i.e P225/65R16. 
What is the load rating molded into the tire?

You reported a 7400 dry wt.  Since then, you have filled the Propane tanks, added bed linens, pillows, towels, soap, shampoo, TP, pots and pans, dishes and silverware, glasses, mugs, food, drinks, lawn chairs, drain hoses, water hoses, water pressure regulator, .......  and the trailer weighs a LOT more than 7400#!  It will be MUCH closer to the 9500#  GVWR and your tongue wt will - or should be - 1,000# or more.

If you have 600# total passenger weight PLUS 80# WD hitch PLUS 520# cargo in the bed PLUS 1,000# tongue wt, then your truck is carrying 2200 pounds and you are GROSSLY OVERWEIGHT.  That is why we ask the questions - to try to keep you safe.
 
Back in the day when tuning race car suspensions I would use a tire pyrometer to the check the temperatures across the tread of the tire. I still use this method to determine proper inflation values on the TV and trailer. I keep a log of this and occasionally recheck after changes have been made. With the cheap availability of point and shoot digital thermometers this is an easy task to get the pressures set perfectly for each individual wheel regardless of loading.
I will have a piece of paper with LF, RF, LR, & RR properly put on a page of letter sized paper. Under each tire location I designate O M  I  to designate Outside Middle and Inside of the tread in the proper location for each tire. I then drive the vehicle at highway speed for about 10 miles to allow the tires to obtain temperature. Next I safely and quickly pull to a stop and point the pyrometer at those tire areas to get the real temps across the tires. This is as accurate as you can get. If the temps are higher in the middle of the tire they are over inflated, higher edge temps indicate under inflation. Taking too long to recover temps allow the tire temps to average together skewing results. More info can be obtained from this as excessive camber can be ascertained as well.
Hope this helps...
 
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