You can soften the ride by using a lower pressure tire. But you can't just put less air in the tire because it still has to support the weight, so you want a tire with a bigger footprint. That means more squaer inches of rubber in contact with the road, allowing a lower pounds per square inch (psi)to get the required support.
You usually get a bigger footprint by getting a wider tire, if your wheel wells have room for them. Less rigid sidewalls also help broaden the footprint. However, both of these things are potential problems with dual wheels, becasue there is a limited amount of space between the two tires. You must be careful to maintain adequate spacing or the tires will rub against each other and quickly wear out. So, you have to do some homework. FIrst you must know the weight to be supported on each axle, so you can look up the required tire pressure for each tire you are considering. Then you must know the space now available between your tires and check how much will be left if you change to another model or brand. Same for the space in the front wheel wells, wear you must be sure the different tire will not scrub the fender well in a tight turn. Tire dealers have all the spec information on each tire they sell - tread width, rolling radius, required dual spacing, and the psi needed for any given load. A good dealer will get it out and show you. Most of them will wing it and say, "Oh sure, plenty of room". A heavy truck tire dealer is more likely to know his stuff than the guy who deals primarily with passenger cars every day.
If your rig currently has Michelins, you may find that Goodyears will allow lower pressures for the same load.
And once you know your axle weights and therefore the actual tire load, you may find that you can use less psi in your existing tires. That would soften the ride, especially if on the fronts.
2004 American Tradition; 2013 Buick Verano
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