I wouldn't worry about the tires yet, keep your money in your pocket. Just be sure you check them and they are in good shape. I run my tires 10 years on my TT before I replace them, but I take good care of them. Be sure they are not underinflated because that will create heat and heat is not good for tires. On the tire decal it will tell how much to inflate them (probably 50 psi on those 15" ones). Most trailer tires are rated for 65 miles an hour what is also a safe travel speed with a combo. Some states might even have a lower speed for combo's.
2014 Ram 1500 CrewCab 4x4 5.7 Hemi 3.92 Rear and Air Lift 1000
2005 Jayco Jay Feather LGT - 29Y GVWR-6500 lbs.
Pro Series 1200 lbs. WDH with Double Sway Bar.
Champion 3100/2800 watt Inverter/Generator-Onboard Solar Power
ALJO 'Forever Young @ Heart' provide on their travels Music Entertainment to Senior Care Homes