I'm cheap. Do you put new tires on your truck every year? Every couple years I go to the junk yard and I don't know how but this guy gets incredibly nice 235/75/R16's duellers. I don't know where they come from but they are 40 bucks a tire, damn near brand new. It's a work truck and it's a dump truck it doesn't need 200/per tire tires on it. The tires pretty much match too. 160 for all four, had a buddy mount them and ready to roll, that was two years ago and I may squeeze another two more out of them. Steer tires I honestly can't remember when replaced them but they pass inspection every year and don't go flat. Trailer tires... I gave up on buying good trailer tires, I blow through them. Pivoting on the tires wears them out quick, plus it seams I always pick up nails or have one go off the bead and ruin it so I buy them cheap too. I bought 4 good tires one year and 2 of them made it till the end of the season that was enough. So trailer tires run me about 150 a year. Mower tires, two seasons so 100 bucks a year. My equipment looks good and I don't care what name is on the tires as long as they stay inflated, I've bought nice tires and have learned my lesson, I put my truck through hell sometimes and expensive tires go flat just like the cheap ones. So all in all, yes I would spend on average of like 300 bucks per year on tires... so 25 per month.
As for support equipment here's how I look at it. If I were an accountant I would still have an air compressor, a garage full of tools, a computer, boots ect. Yes they are business expenses but if I weren't in business I would still have them so I don't get nearly as wrapped up in what they cost because they are things I would have anyway. Might not be the right approach but that's the way I look at it.