Tires (and wheels) are an especially popular topic among Corvair owners. For those who want to keep a “stock looking” appearance, this means going on the hunt for 13″ tires. Easy peasy in the 70’s, 80’s and 90’s when compact cars (and trucks!) were all the rage and many cars were running on 4 lug wheels wrapped in a 13″ tire.
As trends change, the 13″ tire has gone out of vogue along with the compact car and truck. What this means for us is a more limited selection of 13″ tires. Folks new to this arena may be browsing for tires online and think they’re getting a deal on a set of 13″ tires for under $150 without reading the fine print.
Here is a useful, well written article from Alvin Reyes at Jalopnik that we thought was worth sharing. (We don’t use cookie trackers and your memberships and donations help pay for this website so we don’t need ads.) Below is the part of the article as it pertains to us. If you want to learn more about tire geometry and physics for your trailer, check out the full article at Jalopnik.
Trailer tires are of a different breed than passenger car tires. Also known as Special Trailer (ST) tires, they are built stiffer to enable higher load capacity, hold more air pressure, and mitigate sidewall flexing, which helps reduce trailer sway. They are often constructed from tougher steel belts and substantial wires for maximum strength. Besides that, trailer tires are constructed from compounds with more antioxidants to resist the damaging effects of UV rays, sunlight, and ozone that may lead to premature dry rot.
Unlike car or SUV tires with softer, more flexible sidewalls designed to absorb bumps, trailer tires are designed to do the opposite. That doesn’t make them inferior, though, since a stiffer sidewall mitigates compression or deflection, enabling them to literally stand tall under load. Just as an underinflated tire accumulates more heat, the rigid construction of trailer tires helps keep them cooler on long hauls. ST tires also have shallower treads than car tires — where new passenger car tires have average tread depths of 10/32 to 11/32 inches, trailer tires start at around 8/32 of an inch, and that’s not a bad thing.
Shallow treads equate to less rolling resistance and tread squirm while under load. The contact patch or tread footprint – the part of the tire that’s touching the road at any given moment — would typically twist and squirm as it steers and rolls down the road in response to the vehicle’s weight. Trailer tires are designed for carrying loads and not to steer or power the vehicle, and their robust sidewalls that resist deflection make them less likely to buckle, compress, or squirm.
Trailer Tires Come In A Different Size Group
Trailer tires may have stiffer sidewalls and tougher construction overall, but they typically come in smaller sizes than passenger (P) and light truck (LT) tires, with taller aspect ratios and narrower widths to manage heavy-duty hauling and towing. The aspect ratio is just one of many numbers and codes written on a tire’s sidewall, and it refers to the height of the tire’s sidewalls in relation to the tire’s width. A lower aspect ratio means the tire’s sidewall is shorter, as is the case with low-profile tires for sporty cars and crossovers.
Skinnier tires with higher aspect ratios are more beneficial to trailers, since a narrower contact patch exerts more pressure per square inch and enables the tires to track better under heavy loads. Using tires that are wider than what the manufacturer recommends for your trailer could cause wandering or make unnecessary movements or vibrations that exert more stress on the trailer tongue.
SFBA also has a tire and wheel primer in our FAQ section. We’ll save you the search. You can click here to learn more about selecting the correct tire for your Corvair.
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