Tires
hard DIY~1h jobWritten in plain English and reviewed by the eli5cars editorial team · Last reviewed June 2026
What it does
Tires are the only part of your car actually touching the road, and they're a wear item, not a lifetime part — the rubber tread and the internal cords wear down and age out over time no matter how well you maintain everything else. Tread depth determines wet-weather grip and hydroplaning resistance; the classic penny test (insert a penny with Lincoln's head upside down into the tread groove — if you can see all of his head, the tread is too shallow and it's time to replace) is a free way to check. Tires also age out even with tread left: rubber compounds harden and become brittle over 6-10 years regardless of mileage, so a tire that looks fine can still be unsafe on an older car. Buying tires yourself online and paying a shop to mount and balance them is usually cheaper than buying through a shop's in-house selection, but it still requires the shop's equipment — this isn't a driveway DIY job like a brake pad swap.
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DIY Cost
~$520
parts only
Shop Cost
~$800
parts + labor
Estimates only — real prices vary by region, vehicle, and shop. Updated 2026.
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DIY tutorial
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Frequently asked questions
What is the penny test and how do I do it?
Insert a penny into a tread groove with Lincoln's head pointing down into the tire. If the top of his head is covered by tread, you have more than 2/32" of tread left and you're generally fine. If his whole head is visible, your tread is at or below 2/32", the legal minimum in most states, and it's time to replace the tire.
Do tires expire even if the tread still looks good?
Yes. Most tire makers recommend replacement at 6 years from the manufacture date regardless of tread depth, and almost all recommend replacement by 10 years maximum. Rubber hardens and cracks with age and heat cycling, which reduces grip and increases blowout risk even on a tire that looks barely worn. Check the DOT date code on the sidewall (a 4-digit code, e.g. "2321" means the 23rd week of 2021) to find the actual age.
Should I replace 2 tires or all 4 at once?
If your car is front-wheel or rear-wheel drive and only one axle is worn, replacing just that pair (always as a matching pair on the same axle) is usually fine. All-wheel-drive vehicles are pickier: many manufacturers require all four tires within a very close tread-depth tolerance to avoid damaging the drivetrain, so replacing all four is often required, not optional, on AWD vehicles.
What's the cheapest safe way to buy new tires?
Buying tires online (Tire Rack, Amazon, or a retailer's website) and having them shipped to a local installer for mounting and balancing is usually the cheapest route, since you avoid the shop's retail markup on the tire itself while still paying for professional installation ($15-25 per tire for mounting/balancing, roughly $80-100 for a set of four). Comparison shop installer prices too — they vary more than people expect.