Trailer tires usually fail by age, not mileage — a trailer that sits parked most of the year can blow a tire with plenty of tread left because the rubber dried out and cracked while it sat. San Antonio Tire Shop checks the manufacture date on every trailer tire it sells, not just the tread.
Trailers don't get driven daily, which is exactly why their tires fail differently than the ones on the vehicle towing them. A tire that sits under a trailer for long stretches between trips ages from the inside — UV, heat, and time crack the rubber compound even while the tread looks nearly new. The tire usually gives out on the highway, loaded, at speed, which is the worst possible place for it to happen.
ST-rated trailer tires aren't interchangeable with the passenger or light-truck tires most people are used to buying — they're built for a different kind of load, carried differently, at different speeds. San Antonio Tire Shop covers roughly a dozen service areas around San Antonio, so a trailer tire that fails on the way to a jobsite or a boat ramp outside the city doesn't necessarily mean driving all the way back into town.
Why do trailer tires fail even when the tread still looks good?
Time does more damage than mileage on a tire that mostly sits still. Heat cycles the rubber expands and contracts with; UV breaks down the compound from the outside in; and a trailer parked on concrete or gravel for weeks develops flat spots and cracking along the sidewall that isn't visible from a quick glance at the tread. None of that shows up as wear — it shows up as a blowout on the interstate.
Are trailer tires actually different from truck tires?
Yes — ST (Special Trailer) tires are built with a stiffer sidewall than a passenger or light-truck tire, specifically to resist the sway a loaded trailer puts on a tire that wasn't designed to carry weight that way. A few things separate a trailer tire from what's already on the tow vehicle:
- Stiffer sidewall construction to resist trailer sway, not steering feel
- A load rating matched to the trailer's rated capacity, loaded — not the tow vehicle's
- ST marking on the sidewall, which is not interchangeable with a P or LT rating
How do I know if my trailer tire is too old to trust, even if the tread looks fine?
Check the manufacture date stamped into the DOT code on the sidewall rather than judging by tread. A trailer tire that's been sitting for several seasons can look nearly new and still be a blowout risk once it's loaded and running at highway speed.
Can I put a regular tire on my trailer if it's the right size?
It'll usually mount, which is exactly the problem — the size can match while the sidewall construction and load rating don't. A trailer tire needs to handle sway and load the way a passenger or light-truck tire wasn't built for.
What should I do if I get a flat trailer tire on the way to a job or the lake?
San Antonio Tire Shop covers roughly a dozen service areas around the city and is open into the evening on weekdays, so getting back to the shop at 4510 W Commerce St before closing isn't always the scramble it sounds like — call ahead with the trailer's tire size so a replacement can be ready rather than sourced after you arrive.