Shouldn't be THAT hard
Getting decades old rubber OFF the rim can be a huge effort but presuming that the tire and rim are the same size getting the new tire on should be a lot easier. The hardest part about getting the new tire on is being very careful that you have the portion of the bead already on the rim in the depressed center of the rim. That is what provides the "slack" needed to get the rest of the tire bead over the edge. If you think that you can stretch the steel bead wires over the rim like a cheap bicycle tire you are going to be disappointed, those beads are tough. I am a big believer in using Yamaha Tire Mounting Lube because it stays wet long enough and then really does dry but many will say dish soap and water or WD-40 will work as well or better. Use what you like or have on hand but use something! There are lots of little "tips" that can make the job go better, taping the edge of an old car wheel and using that to set your bike wheel on can give you a more stable work piece while protecting brake rotors, hubs, bearings, etc. Using real tire irons rather than screw drivers and pry bars helps a lot as well. I usually just work on a couple of 4 x 4 blocks on the tailgate of the truck, If I have a second set of hands to hold the rim, the tire can often be "screwed" on to the rim once it is half way.
Some combinations can be a challenge but usually, at least when installing tires - 'If it is hard, you are doing it wrong'
No one calls the Fire Department because they did something smart!
06 DR 650, Moose RS Holder, Handguards and Skidplate, ProTaper bars, Garmin 60CSx, Motech racks w/ 20mm Ammo cans, Renazco, TKCs summer/17" SM wheels winter 08 Scrambler, Conti Trail Attacks and BlackTiger Fork mod, 05 FSE 450, 03 KLR 250, 02 FXDX, 72 WR 250 (again), 72 SL 350 K2 (again), 72 TR6R, 06 XT 225