Wannabe making cost calculations for o/o

Your questions are valid, but there are a number of variables. Tire life and mpg are as much related to the driver and how he handles the equipment than the equipment or terrain. If you check tire pressure regularly and keep air at the same point, it will prolong the life of your tires. Terrain is important, but not as much as the habits of the driver. You can blow a tire at any time. I would expect steer tires to have a life of 80,000-150,000 miles on average. You could get more miles from your steers with good maintenance such as having regular alignments. I would expect that driving on tar and gravel roads would reduce the life of tires somewhat over running on asphalt. In doing calculations, I would be confident of the range that I listed. If others are getting 6 mpg, then I would expect that you could do the same. When I do estimates I use 5 mpg. It is best to expect lower mpg than to over estimate your fuel economy. When it comes to calculating fuel consumption from loaded to empty, you could get 1+ mpg empty, depending on terrain and conditions. If you drive in an area that has a lot of wind or mountains, then your mph will likely be lower than if you drive mostly on flat roads.

 

I would expect to get about 150,000-250,000 on drives. Again, it will still depend on your air pressure being checked regularly. I have heard some say that they have gotten as many as 400,000 on their drives with Michelin. I doubt you would be able to get that many, especially with the type of road that you will be traveling. You should be able to get comparable miles as I noted on your trailer unless it is a spread axle. You may not get more than 80,000 on a spread axle tire. If you have a spread axle with a dump valve then you should be able to get more miles from your tires.

It will nearly always come back to the driver and how well you do your pre-trip and maintenance. You will blow tires from time to time and that will skew your average miles per tire. Keeping tire pressure up will minimize the possibility of a blowout.