2025-08-01 · 5 min read
What to know before you replace trailer tires
ST sizes, load range, speed rating, and whether to buy a mounted assembly — a practical guide before you unbolt the old wheels.
Trailer tires are specified as ST sizes (for example ST205/75R15) with a load range letter. That letter is not optional. Dropping a load range C onto an axle that was spec’d for D is how heat builds and sidewalls fail on the highway.
Replace tires in pairs on an axle, and keep construction consistent — all radial or all bias. Check the wheel for cracks while the tire is off. If the wheel is ugly but sound, a mounted tire-and-wheel from the shelf may still be cheaper than a roadside change later.
Inflate to the pressure on the tire sidewall when cold, not to the tow vehicle’s door sticker. Recheck after the first loaded trip. Store the trailer so tires are not parked in a rut or against a hot wall for months.
We stock common ST sizes as tires only and as mounted assemblies. Call Flint, Grand Rapids, or Traverse City with the size and lug pattern, and we will tell you what is on the rack.
Need the part that article mentioned?
We do not publish prices online. Call the store closest to you — we will check the shelf and special-order anything we do not have in stock.