open up the phone book and look up "auto tires" and just start calling 100 plus places that sell regular car/truck tires. it will take some times. but after so many calls someone more likely knows a telephone number or name of a place. and you just need to be ready to jot the name / phone number down quickly.
if you do a internet search through some phonebook website. look up agriculature or ag tires, or farm or something like that. and lookup for places a couple hours away. prices can vary widely.
if you are wanting tires installed for you onto the rims. it may be easier for a given place to just come out and pull off old tires and put new tires on, right at your place. there is a service fee for doing this, and price can vary widely. if you are wanting rear tires filled with a liquid. then it would be extra fee of course, but most likely who ever comes out for service to do tire swapping, already has a setup in there truck to fill the rear tires up with a fluid.
was told for large tires, they prefer to have tire still mounted to the tractor. so they can use the tractor itself, to hold the rim, while they pop the old tire off / put new tire on. vs trying to jack around with a tire laying on the ground.
there are name brand tires, and off name brand tires. some dealers will only deal in certain brand/s of tires. and for some name brand tires cost is 2x compared to off brand tire manufactures. what the difference is i do not have a clue.
again just start callling 100 plus places that sell regular car/truck tires in phone book, to find the local places that deal with tractor tires. and then do a internet search for a couple hours away.
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for me, i found a place i want to say 1.5 hours away from me, and including service fee for coming out to me for putting on new tires, plus miles, and 2 tires, with tubes, and got a higher ply rating, it was cheaper by a couple hundred bucks vs someone locally.
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my question is what caused the front tires to wear? are you running on hard dry dirt or pavement / concrete a lot? with 4WD engaged? is tractor/tires that old and just over time have gotten that way?
check and find out cost, for replacement for all 4 tires. different tire brands may have different outside diameter contact the various tire dealers near you. and see what they recommend for the given brand and size of tire that will fit your tractor.
what do you use the tractor primarily for? and other misc tasks?