Re: Bumpy Roads
Reply #16 –
Living in so cal with concrete block freeways made me change the suspension and tires and shocks to improve the ride quality and noise.
Most other brand tires "H" rated tires are 6700 pounds at 120 for singles.
Michelin's seem to be the only brand that has their rating at 7160 pounds.
That allowed me to lower the tire pressure 10 pounds for the same loads as my previous "G" rated Michelin's.
It seems likely also that the thicker tread depth on the Michelin's might also contribute to the noticeable ride improvement plus the latest XZA-3+'s tire design was designed to ride better and quieter.
That being said at my 97/87 pressure I run a small amount of tread squirm seems to be present but the directional sipes that this tire has seems to make the tire go straight.
On top of it the tire seems to "dive" in nicely when turning. Almost a small transition "thing" from the self straightening directional sipings effect then to the cornering turn in.
The Michelin specs mention the sipes only work for the first 50% of the tread,
Quite possible that the sipes are not needed after the tires wear down that far as any tread "squirm" effect seems to go away as the tread block is worn away.
Sounds like I am a tire engineer which I am not. Just a careful observer.
Plus the Komi FSD's.
Between the thicker tread block and the higher capacity "H" rated tires allowing lower tire pressure for my loads and the shocks the sharp kickback from square edges has been greatly reduced.
Five or less pounds too high or too low is noticeable fo me in driving the coach.
Just right makes the steering and ride quality noticeably improved.
Fixed countless rv's long ago suffering from too high of a tire pressure that hurt the owners ride quality.
As mentioned the scaling of the coach is necessary and then referring to the manufacturers pressure vs load chart is needed.
Had a similar problem on two of my old Lexus cars.
Both required tire changes to new Michelin primacy tires to lower the tire noise, greatly improve ride quality and steer straight.
Those particular model tires were noted to help all three issues.
If you drive nice asphalt smooth roads versus the chopped up so cal freeways then your tire and shock choices may allow less expensive choices.
Although I have driven other brand tires long ago who soaked up the square edges fine. The penalty to me was the somewhat numb steering. Works but no sharp "feel" to the driving.
I made a game with myself long ago when I was in the sales management of different brands rv stores here in so cal.
I would not look at a coaches tires before I drove it. At least for me I could tell which coaches were on Michelin's.
Every time. Remember I was looking for anything wrong and how well the coach drove had a direct relationship to the resale abilitiy and the price I could get for the coach.
Probably just like Foretravel did/does new, the better the ride and handling and road noise the easier the coach was to sell.
Almost universally I changed nice coaches with worn or older or poorer riding and steering tires to new Michelin's to help my sales and to increase customer satisfaction and therefore my repeat business.
On smooth asphalt roads the differences are greatly reduced as far as ride and noise.
On concrete block roads that are worn the differences are magnified.
Highest possible capacity that then allows a lower pressure then the shocks worked well for me.
Shocks and other brands are reported to work well also but as stated I noticed the lack of steering "feel" the oem Michelin's produced.
Both of our old lexus's had the same exact problems on the so cal freeways and were both greatly helped with the latest Michelin products specifically designed and marketed to address these exact issues