What are Summer Tires?

When it comes to tires for sedans, coupes, minivans, and crossovers, there are a few broad segments of tires to choose from. All-season tires are designed as a jack-of-all-trades, do-it-all compromise that delivers long, even wear, a comfortable ride, low road noise, predictable handling, and year-round traction. All-weather tires check all the above boxes, except with more of an emphasis on winter traction (and a tread compound and tread pattern that reflects that). Winter tires are just what the name says: they’re designed specifically for traction in snow and slush, and use a softer, more pliable rubber compound that will wear quickly on warmer days.

Touring tires are designed for the same performance as all-season tires, but with a quieter and more luxurious ride for long hours on the interstate. Then you have ultra-high-performance tires, who are derived from competition-grade racing tires and are designed for sharp, responsive handling, high-G cornering ability, great braking traction, and, in general, performance that’s as tight and precise as a track-only race car.

Summer tires are similar to UHP tires, though they don’t necessarily offer as high-end performance as their more performance-oriented counterparts do. They’re designed for traction in wet or dry weather, but summer tires come with some fairly significant tradeoffs that we’ll discuss below.

The benefits of summer tires

The basic performance and design parameters of summer tires include:

• Shallower tread grooves and more rubber-to-pavement contact, which allows for quicker acceleration
• Wider, flatter footprint for improved handling and braking traction
• High speed ratings allow the tire to be used at higher speeds
• Rubber formulation that’s engineered to be softer and “stickier” for improved adhesion to the road
• Shoulders are designed for great grip during hard cornering
• Rigid steel belt and fabric ply package for less tread flex during hard cornering
• Stiffer sidewall (in some cases) for enhanced handling

In other words, summer tires are specifically designed for drivers who love to carve up a twisty mountain road or put in time on a skid pad or track. They deliver excellent handling on dry pavement and competent traction on wet days, which makes them a great choice for sporty sedans, coupes and crossovers.

The science behind summer tires

So summer tires need to fit on the rim, fit in the wheel well, stay seated on their bead, support the vehicle’s weight and hold up under hard cornering and G forces without any signs of separation or uneven wear. That’s all with ride quality and noise levels that are tolerable for day-to-day use. How does a tiremaker meet these expectations for summer tires?

• Shallower tread depth: The shallower tread of summer tires puts more rubber in contact with the road, but it also helps with heat dissipation (heat buildup is the enemy of any tire). This might be a disadvantage in terms of wear properties, tire service life, and wet-weather traction, but it definitely pays off on hot, dry pavement.
• Softer, stickier tread compound: In some cases, this tread formulation is so soft that you can make an indentation in it with your thumbnail. Think about a pencil eraser, and that’s how soft the rubber compound of some summer tires can be. That soft rubber is the perfect solution for adhesion to the road on most surfaces, especially in hot weather. For these advanced tread compounds, chemical engineers have discovered all kinds of innovations in materials, including things like citrus. soy or sunflower oils, enhanced amounts of silica and even ground-up walnut shells, all of which help with grip and wear properties.
• Rayon fabric plies instead of polyester: This might seem pretty esoteric, but there’s definitely a reason behind it. Rayon fabric is made from purified cellulose fibers (derived from wood pulp) and offers better directional stability, good dynamic performance and better resistance to heat buildup, making them a superior choice for the demands of summer tires.

Summer Tires vs. All-Season Tires

There are some real contrasts between summer and all-season tires. Even though they usually don’t perform well in heavier snow, all-season tires can be used year-round thanks to a tread compound that’s engineered for hot and cold temperatures. All-season tires also are designed with a network of sipes, tiny hair-thin slits that are cut into the tread surface and add thousands of extra biting edges for grip in wet or wintry conditions as well as improved dry-weather traction. All-season tires also feature deeper grooves that evacuate water from the tire’s contact patch, for improved wet-weather grip and resistance to hydroplaning. The target is a tire that can offer year-round performance along with handling that’s consistent and responsive, if not as precise and sharp as UHP or summer tires.

Summer tires have the design considerations mentioned above, but their tread formulation makes them a poor choice for year-round driving. If temperatures are consistent below 40-45 degrees Fahrenheit, the rubber compound of summer tires will stiffen up and lose traction, making them downright unsafe. Think about the difference between a rubber boot and a hard-rubber hockey puck, and on a cold day that’s like the difference in traction between all-season and summer tires.

Summer tire maintenance

Tire makers advise that summer tires shouldn’t be used if temperatures are below 40-45 degrees F, for safety’s sake. If you’ve got a performance-oriented ride, you should store those summer tires stacked on top of each other in a cool place that’s out of direct sunlight. For a little added degree of protection, tire storage bags are available; for some tire storage bags, you can suck the air out of them with a shop-vac and then seal them up. Failing that, you can put each tire inside a big garbage bag and seal it securely with duct tape.

Other tire maintenance details aren’t much different from any other tires. Rotate them every 5,000 miles, watch your tire inflation levels, keep an eye out for premature or uneven wear, and regularly inspect them for damage and any debris or foreign objects in the tread or sidewall.

When to switch to summer tires

Like we mentioned above, it’s inadvisable to use summer tires on colder days, when temperatures are below 40-45 degrees F (and certainly not if temps are anywhere near freezing). But in late spring when things are starting to heat up and summer is around the corner, you should be safe putting summer tires back on your ride again so you can get out there and thrash that car through the tight corners and twisty roads.

How to know if your tires need to be replaced

Tire replacement cues for summer tires aren’t much different from any other kind of tire:

• Watch for signs of uneven wear, which could also point to alignment, steering or suspension problems
• Watch your tread depth and check it regularly. Minimum tread depth by state law is 2/32”, and a great way to check is to take a penny and insert it into a tread groove. If the tread reaches the Lincoln memorial, your tread depth is 2/32”. Try again with a quarter too with Washington’s head down. If the tread reaches George’s head, your tread depth is 4/32”. One more time with a penny, Lincoln head down. Does the tread reach the top of Lincoln’s head? Your tread depth is 2/32” and your tires are due to be replaced.
• Be aware of any dropoff in traction while braking and cornering, or any changes in wet-weather traction.
• Keep an eye on the tire’s sidewall for signs of weathering or cracking due to ozone and ultraviolet rays.
• Watch the tread area for debris, punctures, cuts or any signs of tread separation.