Gone thru two sets of tires on my 2018 2500 Cummins first was the 20” OEMs Firestone now the 20” Michelins and don’t have 50K on the odometer; I have never towed significantly - have an 18 foot boat; live in rural area of Arkansas mostly two lane paved highway and leveled gravel roads for about 5 miles to home 50% two lane paved highway; 25% interstate; 25% sealed gravel road; I have adjusted my rear PSI down from the 80PSI to 60; Front to 65; two questions what tires do I need to get better mileage; what else to improve mileage on tires