Free ride mods - results after a long trip.

For those that care, I was struggling a bit with ride and road feedback on my ACE – F53 Chassis. It drove OK on smooth pavement off the lot - for the first 6 mos, but any sort of harsh road like concrete provided a lot of feedback through the cabin. It also felt squirrely and “loose” in initial trips. Trying to tweak it the best I could - the first thing I did was the sway bar adjustment. Front first then a few trips. Big difference in decreasing truck push and wander. Then I did the rears, reversing the z brackets. Again, huge difference in stability and tracking. But the largest improvement was getting my tires set right. The plaque says to run my tires at 83 PSI. Without weighing a coach, you are in a sense taking the manufacturer’s word for it. They had it labeled as a 16k # coach. So I loaded it up, and had it weighed (each axle – couldn’t find a 4 corner place). Low an behold fully loaded, gear food, water, fuel, it came in just over 15k #. So according to Goodyear I was way over PSI at 83 for that weight. Before I adjusted anything and took a trip I thought it smart to get a TPMS. TST to be specific. TST by the way is an excellent company to deal with. Anyway, I thought it made sense to monitor Psi and temp if I was going to adjust the tires. I just felt better and if any adjustment I made caused an issue, I would be alerted immediately and could make an adjustment before any catastrophe. The TST worked flawlessly. So I adjusted the fronts to 76 PSI and the rears to 80. I am sure I could have gone to 78 in the rear but there was not as much space between the duals as I would have liked at 83 so I didn’t want to risk rubbing. All set and ready to head to Fla. MAN what a difference! No wander, MUCH quieter, MUCH smoother and overall a far more enjoyable ride. I never realized how tiring a harsh drive could be. 8-9 hours in the saddle per day and I still felt fairly fresh. The Psi climbed about 10-15 per tire but the temps stayed within 10 degrees of ambient so no issues as far as the Psi adjustment. This all appears normal. So the moral of the story is, that coaches off the showroom floor are not set up to drive correctly. There are things you can do with little or no cost to get a better ride. Thanks to all who made me get a weight. One of the best things I did. I cannot stress enough how critical this is. Not only for safety but for adjusting PSI accurately. That’s the biggest difference. So for all complaining about their gasser ride, try these things. I am so pleased with the results. It’s no DP but I am convinced it’s about as good as I can get it without throwing a bunch of money at it.

Class A

23 Replies

jadatis
Explorer
Apr 24, 2014
If we want to get back to the original topic, give the tire data like maximum load and needed pressure for that ( or loadkind, I think F-load with maxloadpressure of 95 psi) and I will calculate what the advice would be with my spreadsheet. Then you can compare that with your experiénces.

But I only noticed the strange difference in temp and pressure so made notice of that. Dutch after that confirmed that external sensors do not measure the inside tire temp extactly.

so it can still be that you have a weightdiffence R/L per axle, but do not see that in the different temperatures, because the measurement of that is insecure.
Effy
Explorer II
Apr 24, 2014
Yep, overthinking. I was simply trying to offer my experience after a few free mods and the difference it made to the ride. Perhaps we should open a new thread on the tire wear, molecular structure and stress testing. In it's current state the thread sort of loses it's purpose and has morphed into something else entirely.
jadatis
Explorer
Apr 24, 2014
wolfe10 wrote:
Some "overthinking" going on here. The tire manufacturer engineers have already looked at these factors and taken them into consideration when the published the Tire Inflation Charts.

Weight the coach (4 wheel position best). Use heavier wheel position on each axle to to to the chart. The chart number is the minimum PSI for that weight. Add 5 PSI to it for a safety factor. Adjust seasonally with big swings in ambient temperature. PERIOD.

Again "cold" pressure is pressure at current ambient temperature-- be it 30 degrees F or 100 degrees F. Same for all tire manufacturers.

In fact its simple. What is called cold pressure is when the temperature inside the tire is the same as outside the tire.
By driving the bending of the rubber warms the inside tire temp up.
But also by sunshine on the black rubber can heaten up the tire inside air. But also the heat of the brakes transported trough the rimms can heaten up the tire inside.
What is important for not damaging the tires by driving is only that heatening up by the bending of the rubber .
If the tire inside air is 115 degr , some parts of the tire can be for instance 200 degr because not every part of the tire is bending as much.

Heard from a man of a tire company that at 170 degr Celcius the rubber looses its flexibility permanently, and then gets damaged by bending.
probably even at 130 degr C/ about 300dgr F this proces already begins.
But if the tire inside is for instant boiling point of water so 100dgr C /about 200dgr F by the heat of brakes or sunshine , all the parts of the tire can be below 130dgr C/300F so no hardening of the rubber and so no damage.

If by only driving the tire inside for instance only 70dgr C/??F then its possible that sertain parts of the rubber of tire are above 130degr C/300F and the rubber handens so damage to tire.
Daveinet
Explorer
Apr 23, 2014
wolfe10 wrote:
Some "overthinking" going on here. The tire manufacturer engineers have already looked at these factors and taken them into consideration when the published the Tire Inflation Charts.

Weight the coach (4 wheel position best). Use heavier wheel position on each axle to to to the chart. The chart number is the minimum PSI for that weight. Add 5 PSI to it for a safety factor. Adjust seasonally with big swings in ambient temperature. PERIOD.

Again "cold" pressure is pressure at current ambient temperature-- be it 30 degrees F or 100 degrees F. Same for all tire manufacturers.
Brett, the problem is that 4 corner weighing is not available to him, so he needed some alternative confirmation that he was OK.
tderonne
Explorer
Apr 23, 2014
So, as you found, with the right tire pressures, your rig, that's just a few hundred pounds under it's max weight (not thousands) rides quite good. Excellent!
Effy
Explorer II
Apr 23, 2014
tderonne wrote:
Effy wrote:

The issue with a light coach, especilly 15k on a 23k chassis is I have little to no sprung weight.

You don't have a 23K coach. Ford doesn't make one. You mean 16k or 18K, right? Like another poster mentioned?

Yes sorry was thinking about GCWR. GVWR is 16k
tderonne
Explorer
Apr 23, 2014
Effy wrote:

The issue with a light coach, especially 15k on a 23k chassis is I have little to no sprung weight.

You don't have a 23K coach. Ford doesn't make one. You mean 16k, right? That's what you said in your first post to what the label said. You thought that was your weight maybe?
wolfe10
Explorer
Apr 23, 2014
Some "overthinking" going on here. The tire manufacturer engineers have already looked at these factors and taken them into consideration when the published the Tire Inflation Charts.

Weight the coach (4 wheel position best). Use heavier wheel position on each axle to to to the chart. The chart number is the minimum PSI for that weight. Add 5 PSI to it for a safety factor. Adjust seasonally with big swings in ambient temperature. PERIOD.

Again "cold" pressure is pressure at current ambient temperature-- be it 30 degrees F or 100 degrees F. Same for all tire manufacturers.
jcthorne
Explorer
Apr 23, 2014
The CHF made a big difference in our 20,500 F53. The next biggest improvement came when we finally got rid of the GY tires and installed a new set of Bridgestones. SO much quieter, smoother and they run much cooler. After 2 blowouts since new, it was time they went goodbye.
Dutch_12078
Explorer III
Apr 23, 2014
Some relevant factors that need to be considered when evaluating tire pressure/temperature changes are not only the ambient temperature changes as we travel, but also the cooling effect of a tire traveling down the road at 65 MPH or so. Also, it must be considered that externally mounted TPMS sensors do not accurately read the internal tire temperature, but rather a relative temperature that's still very useful in determining potential problems. Are all of the tire temps pretty equal? Good... Is one tire temp reading significantly higher than the others? Not so good...