the life depends on proper maintenance ,air pressure, rotation,balancing,vehicle alignment, even proper lubrication of the 5th wheel(where the trailer connects) steering tires will last about 125,000 miles. drive and trailer tires about 200,000 miles.

too many variables.

I got down rated for saying too many variables? un-freakin-believable. I gauge my tires.EVERY DAY..ALL 18. I dont give them a bump like the majority of btm drivers. 110psi stears and 100psi all the rest ...every day,every stop, I make sure the psi is exact. Stears I can get 180-250k miles,except when you have 1 with 55k miles on it it grenades due to a defect and sends you thru the median at 75 mph across on coming traffic lanes down the bar ditch on the other side and thru 100 feet of chainlink fence. Variable #1. other tire still has 85% tread left but wont see a rim on my truck due to the fact that its brother did 15000 dollars worth of damage. I have had 3 stear tires blow out on me in 25 years this was the first 1 where i had 0 control of the vehicle.By the way, the first 15 years of driving i never had a flat stear tire.Drive tires also need to be rotated. back drive axle to front and vice versa.i get 300k on my drive tires except when county road crews digging up cracked asphault and leaving 3lb chunks in the road gets kicked up by stear tire knocks air line off maxi can and locks up 1 axle with 4 tires at 55mph(i know what your thinking dont try me)2 lane road oncoming traffic in place and road crew truck on shoulder = no avoidance although i did slow down from 65mph still flat spotted 4 near new tires 1800 dollars (cha ching) Variable #2. I pull a spread axle trailer.Variable #3 if im lucky i get 1 year on these tires. i dont base it on miles, usually about 500 loads.is the minimum.. spread axles can eat tires for breakfast and give you the dribbles by lunch.they are not the same as standard tandem axle trailers.there are about 8 variables based on driving behaviour with spread axle trailers. i could go on but im not sure about the terms of use for AB ers and length of answer and would hate to lose all i have written. So in the future when someone says "too many variables" please.... dont be an ass hat.. cheers

I'm a transport trailer mechanic and I handle a lot of tires. A good set of quality drive or trailer tires should last about 350,000 kilometers or three to four years. To do this it is very important to keep inflated between 90-100 psi is ideal. Many times flat spotted tires on semi-trailers are caused from brake shoe hang-ups. I've seen this many times, even on trailers with ABS in good working order. I have a product to prevent this and can be viewed on my website. Go to web.me.com/gerrythibeault to find out more. Email me any questions on the subject and I ill be happy to answer.