When it comes to trailer tires, two of the most common heavy-duty options are the ST235/85R16 and the 235/75R17.5 low profile (18-ply) tire. At first glance, they look different because of the rim size—but here’s the truth: these two tires are nearly the same overall height, so you don’t have to worry about clearance issues when upgrading. The real differences are in load rating, strength, and long-term durability.
1. Size & Clearance
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ST235/85R16 (16”): The standard 16” trailer tire, commonly paired with 14-ply load ratings.
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235/75R17.5 (17.5”) Low Pro: Despite the larger wheel diameter, the shorter sidewall keeps the overall height nearly identical to the 235/85R16.
Result: Both options are basically the same height—so no rubbing, no clearance issues, and no modifications needed when swapping.
2. Originally Designed as “Super Singles”
The 17.5” tire and wheel combination actually started out as a replacement for 16” dual wheels on heavy-duty trailers. On 10K and 12K axles, manufacturers originally used dual 16” tires to carry the load. The 17.5” super single was engineered to take their place—providing the same load support with one extra-strong tire and wheel instead of two.
Today, these 17.5” super singles are no longer limited to 10K–12K dual tandems. They’re widely used across 7K, 8K, 10K, and 12K axles, making them one of the most versatile and reliable tire options on the market.
3. Load Rating & Strength
This is where the difference really shows:
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16” 14-Ply Tires
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Rated around 4,000–4,400 lbs per tire (brand dependent).
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Wheels typically rated in the same range (4,000–4,400 lbs).
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17.5” 18-Ply Low Pro Tires (Super Singles)
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Rated at 6,005 lbs per tire.
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Heavy-duty solid wheels also rated at 6,000+ lbs each.
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Practically bulletproof under heavy loads.
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Result: The 17.5” setup offers 1,500–2,000 lbs more capacity per tire and wheel compared to 16”. That’s a huge advantage for heavy haulers.
4. Hub Piloted Bolt Pattern
Both 16” and 17.5” use the same hub-piloted bolt pattern, so upgrading to super singles is straightforward. No complicated conversions are needed.
5. Why Upgrade to 17.5”?
If you’re running lighter loads, 16” tires may get the job done. But if you’re:
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Hauling heavy equipment
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Running long miles and want fewer blowouts
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Looking for the same technology designed to replace dual wheel setups
…the 17.5” low pro super singles are the way to go. They’re stronger, rated higher, and built to last. the 17.5" solid single wheel is rated for a whoping 6,005 lbs per wheel!
While the 16" single wheel is typically rated anywehre from 3600 lbs - 4400 lbs per wheel. Thats a hugh difference!
Final Takeaway
While the ST235/85R16 is still a solid, common choice, the 235/75R17.5 18-ply super singles were originally built to replace 16” dual wheels on 10K–12K axles—and they’ve proven themselves tough enough to now be used on 7K, 8K, 10K, and 12K axles across the board. With 6,000+ lb ratings per tire and wheel, they’re next to bulletproof and the smart choice for heavy hauling.
At Trailer Parts Unlimited, we carry both options—so whether you want the standard 16” setup or the heavy-duty 17.5” super singles, we’ve got you covered.
Shop in-store at Trailer Parts Unlimited – 631 TX 75 N Huntsville TX 77320 (Exit 118 off I-45, next to Pilot and Chicken Express) or online at TrailerPartsUnlimited.com. We offer pickup or shipping nationwide.
235-75R17.5 18-Ply Taskmaster HD Trailer Tire on Solid Silver Wheel 8x6.5"
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ST235/85R16 14-Ply All Steel Trailer Tire on 8 Lug Silver Mod Wheel
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215/75R17.5 16-Ply Taskmaster All Steel Tire on Solid Single Silver Wheel 8x6.5" .19OS