4.80-8 vs. 5.70-8: which trailer tire do you need (and can you upsize)?

The short answer: both sizes mount the same 8-inch trailer wheel, so the swap is physically possible either direction. But our stocked 5.70-8 is a 4-ply, Load Range B tire, and our stocked 4.80-8 is a 6-ply, Load Range C tire — so the “bigger” size actually carries less weight. Don’t upsize by the number on the sidewall; upsize by the ply rating, and check fender clearance first.

This is the mix-up that fills trailer-parts forums one question at a time. Here’s the whole answer in one place, using the two trailer tires actually on our shelf.

Yes, they share a wheel — that’s where the confusion starts

Both 4.80-8 and 5.70-8 are built for an 8-inch-diameter rim, which is why they turn up on the same dollies, boat trailers, and small utility trailers and get treated like they’re interchangeable. The “-8” at the end of both sizes is the rim diameter, not a model number — it just means the wheel measures 8 inches across at the bead. Rim diameter matching is necessary, but it isn’t the whole story: confirm your wheel’s width falls in either tire’s recommended range before you swap, and don’t assume a wider tire drops onto any 8-inch wheel automatically.

The real difference is width and overall height

The first number in each size is section width, and that’s where these two actually split. A 5.70-8 runs noticeably wider than a 4.80-8 — more footprint, more sidewall, and a taller tire overall once it’s mounted and aired up. Both of our stocked trailer tires in this family come from Deestone and Kenda.

About two inches taller and nearly an inch wider — that height difference is the one that catches people out against a tight fender, so measure before you assume it clears. If you’re just trying to picture the two side by side, that’s the whole visual difference.

Load capacity comes from ply rating, not the size number

Here’s the part that trips people up: the wider tire isn’t automatically the stronger one. Ply rating and load range set how much weight a trailer tire actually carries, and our stocked pair runs backwards from what the size numbers suggest.

The narrower 4.80-8 out-carries the wider 5.70-8 by 45 pounds, at a lower price, because it’s built with two extra plies. Load Range B tops out at 35 psi and Load Range C at 50 psi — the standard ceiling for those ratings — so check the exact number stamped on your sidewall before you air one up, since GCT doesn’t publish a house-specific max PSI for either SKU.

One more trap: there’s also a Kenda K478 X-Trac in 4.80-8 on our shelf — same two size numbers, completely different tire. It’s a 2-ply mower and snow-thrower tread rated for 435 pounds at a 20 psi max, built for a lawn tractor deck, not a trailer axle running down the highway. If you’re shopping this size anywhere by number alone, confirm the listing actually says trailer or ST-rated before you buy.

Can you upsize from 4.80-8 to 5.70-8? Measure the fender first

Yes, physically — same rim diameter, and it’s a common swap when a trailer needs more footprint on the road. But “will it bolt on” and “will it fit under the fender” are two different questions, and the second one is the one that actually stops people. Installers generally want at least 3 inches of clearance from the top of the tire to the underside of the fender (some shops prefer 4 to 5 inches) to leave room for suspension travel when the trailer’s loaded, plus roughly 1 to 2 inches of side clearance between the tire and the frame.

The measuring procedure, no tools beyond a tape measure:

1. With the trailer sitting normally (not jacked up), measure straight up from the top of the current tire to the bottom of the fender.
2. Measure sideways from the tire’s widest point (the sidewall bulge) to the nearest part of the frame or fender edge.
3. Compare both numbers to the height and width difference in the table above — about half an inch taller, about an inch wider mounted.
4. If your current clearance is already tight (under 3 inches on top, under 1 inch on the side), the 5.70-8 likely won’t clear loaded and over a bump. Stay with 4.80-8.

If your trailer actually runs a 12-inch wheel instead of an 8-inch one, this isn’t your swap at all — that’s a 4.80-12, a different rim size entirely, and our 4.80-12 size explainer covers it separately.

Which one to actually order

For most small utility and boat trailers replacing a worn 4.80-8 or 5.70-8, buy the same size that’s coming off — that’s the size your fender and your axle rating were already built around. Reach for the Deestone D901 4.80-8 when you want the lower price and the higher load range in the narrower footprint, and the Kenda K397 X-Grip 5.70-8 when the fender has the room and you specifically want the wider, taller tire — just don’t expect it to out-carry the 4.80-8, because at our stocked ply ratings it doesn’t. Both brands show up across the rest of our trailer sizing, covered in the small trailer tire guide, and the full lineup is on the trailer tires page.