Choosing replacement tires: how to match size, load, speed rating, age and type
Read the sidewall code, check the date and pick a tire that fits your weather
Safety Behind the Wheel Foundation built this guide from National Highway Traffic Safety Administration (NHTSA) tire guidance, federal tire and vehicle safety standards, Federal Motor Carrier Safety Administration (FMCSA) tire rules and a National Transportation Safety Board (NTSB) tire safety investigation. Every source is listed at the end.
Why the right replacement tire matters
Tires are the only parts of your vehicle that touch the road. Every stop, swerve and turn depends on four small patches of rubber. The tires you pick shape how well the vehicle brakes, steers and carries weight for years.
Tire problems still cost lives. In 2024, 511 people died in tire related collisions nationwide [1]. So look past brand names and price tags. The real questions are about fit and limits: size, load, speed, age and grip in your weather.
Two 2014 collisions studied by the National Transportation Safety Board (NTSB) show the stakes [6]. In one, the tread came off a 10 year old tire on an SUV. The SUV crossed into a school bus, and four people in the SUV died [6]. In the other, a recalled tire about two years old came apart and a van rolled over, killing two people [6].
For monthly pressure and tread checks, see our guide to vehicle maintenance for safety.
Signs it is time to replace a tire
Tires are usually replaced for one of three reasons.
- Worn tread. The National Highway Traffic Safety Administration (NHTSA) says tires are not safe once tread wears down to 2/32 of an inch [1]. Worn tread hurts most on wet roads, as our guide to driving in rain explains.
- Damage. A bulge, a cut that shows cords, or tread pulling away means the tire is done. Federal rules bar commercial trucks and buses from running on tires with exposed cords or separating tread [7]. Those signs should stop you, too.
- Age. Rubber changes over time, even when the tread looks fine. Some vehicle and tire makers advise replacing tires that are 6 to 10 years old, whatever the tread depth [1]. Some vehicle makers say six years [8].
An NHTSA analysis cited by the NTSB found that about 23 percent of tire related crashes that were towed or reported to police involved tire aging [6]. The report adds that harmful changes in a tire’s properties appear after about five years, on a vehicle or in storage [6]. Low pressure and hot weather also raise the risk of tread separation [6].
Start with what your vehicle was built to use
First, find out what your vehicle was designed for. Two places tell you.
The first is the Tire and Loading Information label, which federal rules require on the driver’s side door pillar, or nearby if that spot does not work [2]. It lists the size of the original tires and the spare [2]. It also shows the cold pressures for the front, rear and spare tires, and the most weight of people and cargo the vehicle should carry [2].
The second is the owner’s manual. Federal rules require it to explain each marking on the tires that came with the vehicle [9]. It must also say where to find the tire’s identification number and how overloading harms handling and stopping [9].
NHTSA’s advice is clear: buy the size that came on the vehicle, or another size the vehicle maker recommends [1]. Safety Behind the Wheel Foundation gives drivers the same advice. A size change is a fitment decision for the vehicle maker, not a sales choice. If you change wheels, the tire must suit the rim. The federal standard expects each rim to be one the tire maker lists as right for that tire [2].
Before you shop, write down the size on the door label and the recommended pressures. Copy the full size line from your current tires if they are the original type. Note anything the manual says about replacing fewer than four tires.
How to read the size code on a tire
New radial tires for cars, SUVs, minivans and pickups must carry certain sidewall markings [4]. The rule covers vehicles with a gross vehicle weight rating, the maker’s maximum loaded weight, of 10,000 pounds or less [4]. Markings include the size, the maximum load rating, the maximum pressure, the word “radial” and the Tire Identification Number [4]. Light truck tires also show a load range letter [4].
Here is how to read a common example, P225/60R17 99H.
Comparison compiled by Safety Behind the Wheel Foundation
How to read a tire size code
| Part | Example | What it means |
|---|---|---|
| Tire class | P | Passenger tire. “LT” marks a light truck tire [4] |
| Width | 225 | Tire width in millimeters |
| Aspect ratio | 60 | Sidewall height as a share of the width |
| Build | R | Radial construction |
| Wheel size | 17 | Fits a 17 inch wheel |
| Load index | 99 | A code for the most weight the tire can carry |
| Speed symbol | H | A code for the top speed the tire is rated to hold |
Do not skip the last two codes. They matter as much as the size.
Two numbers that are limits, not targets
The maximum load rating is the most weight the tire can carry at a given pressure [4]. The maximum pressure is the highest cold pressure the tire can take [4]. It is not the pressure to run. Use the number on your door label instead [1].
Quality grades on passenger tires
Most passenger car tires carry grades for treadwear, traction and temperature [10]. A treadwear grade of 200 should last about twice as long as a test tire graded 100 [1]. Traction grades, from best to worst, are AA, A, B and C, based on stopping on wet pavement [1]. Temperature grades of A, B or C show heat resistance. Sustained heat can break a tire down and lead to a blowout [1].
Use the grades to compare tires, not to predict mileage. Federal rules call treadwear a comparison under test conditions, and real results vary with driving habits, care, roads and climate [10]. Winter type snow tires and temporary spares are not covered by these grades [10].
Match the load and speed ratings
Load capacity leaves the least room for error. The federal tire selection standard exists to prevent overloading [2]. It requires the most weight a vehicle can put on each tire to stay within the load rating marked on that tire [2]. The original tires were chosen with that margin in mind.
A replacement with a lower load index can quietly erase that margin. You may not notice on a short trip alone. The risk grows with a full cargo area, a roof box or a trailer.
Follow these rules:
- Match or beat the load index of the original tires.
- If the vehicle came with light truck tires, stay with light truck tires of the same load range or higher.
- Do not swap passenger tires for light truck tires, or the reverse, without the vehicle maker’s guidance. The two classes are defined and marked differently [4].
- Match or beat the original speed symbol. If a tire you like has a lower one, ask the vehicle maker or a tire professional first.
A speed symbol is a test rating, not a safe speed for any road.
Check the date code before you pay
Every new tire carries a Tire Identification Number (TIN) of 13 characters [11]. The first three identify the plant and the next six are the maker’s code. The last four are the date code, the week and year the tire was made [11]. In NHTSA’s example, a code ending in 0308 means the third week of 2008 [1]. So 1825 would mean the 18th week of 2025.
Only one sidewall must show the full code [11]. The other side may show a partial code without the date [6]. The NTSB reported that about 65 percent of tires in service were mounted with the full code facing in, toward the vehicle [6]. Ask the seller to show you the date before the tires go on.
NHTSA advises checking this date at purchase and knowing your vehicle maker’s advice on when to replace tires [3]. Tires age in storage, too [6]. A tire that is a few years old when you buy it will reach the 6 to 10 year range sooner. Ask for recent stock, and have the date codes written on your receipt.
A word about used tires
You cannot see a used tire’s history. It may have been run low on air, patched or recalled. In the Louisiana crash, evidence on the wheel suggested the old tire had been run underinflated at some point [6]. If you consider a used tire, check its date code and recall status, and have a tire professional inspect it. For the vehicle your family relies on, new tires are the safer choice.
Choose a type that fits your climate and driving
Here is how the main types compare:
Comparison compiled by Safety Behind the Wheel Foundation
Main tire types compared
| Tire type | Built for | Watch out for |
|---|---|---|
| All season | Varied road conditions, with some mud and snow ability [1] | Less effective than winter tires in deep snow [3] |
| Winter (snow) | Cold weather and snow | Look for the mountain and snowflake symbol [4] |
| Summer | Warm weather grip | Not designed for freezing temperatures, snow or ice [1] |
| All terrain | Mostly four wheel drive vehicles, on and off the road [1] | Confirm the load and speed ratings still match |
What the mountain and snowflake symbol means
Federal rules define the snow tire symbol as a three peak mountain, the middle peak tallest, with a six sided snowflake inside [4]. To carry it, a tire must score at least 112 in a packed snow traction test, compared with a standard reference tire [4]. That is a measured result, not a marketing name. Look for the symbol itself, whatever the tire is called.
How to decide
Plan for the worst month of your year, not the average one.
- Regular snow or ice: choose winter tires or tires with the snowflake symbol. NHTSA’s winter advice suggests considering snow tires and checking its tire ratings first [8].
- Frequent rain but rare freezes: weigh the traction grade, and replace tires before the tread wears low.
- Towing or hauling: put load capacity first.
- Long summer highway trips: pay attention to the temperature grade.
Keep all four tires the same type and size when you can, and follow any rules in your manual about mixing tires. Our guide to dedicated winter tires covers seasonal swaps. For technique, see driving in snow and ice.
Where to buy and what to ask
You can buy tires at tire shops, general repair shops, the vehicle dealer’s service department and some warehouse stores. Some online sellers ship to a local installer. Wherever you buy, the same steps protect you.
- Bring the size, load index, speed symbol and door label pressures you wrote down.
- Get a written quote that lists the size, load index and speed symbol of each tire.
- Ask for the date codes of the actual tires to be mounted.
- Compare quality grades, and confirm the snowflake symbol if you need it.
- Check for open recalls. NHTSA’s recall search includes tires [12].
- Ask who will register the tires and how.
- Ask what installation includes: balancing, valve stems or pressure sensor service, wheel torque to the vehicle maker’s setting, and an alignment check.
Why registration matters
Tire makers rely on registration to warn owners about recalls [5]. Federal rules require tire makers to supply registration forms to dealers [11]. An independent dealer must either give you a form at the sale or send your details to the tire maker within 30 days [11]. Dealers controlled by a tire maker send the details themselves [11].
Many tires still go unregistered. An industry estimate in the NTSB report put the registration rate for tires sold by independent dealers at 10 percent or less [6]. From 2009 to 2013, tire recall completion rates averaged about 44 percent [6]. You can also sign up for NHTSA tire recall alerts [5]. Our guide to vehicle recalls and safety defects explains the process.
Installation: the final check
Treat pickup time as your last check.
A new vibration, a pull to one side or a warning light means a trip back to the shop. Recheck pressures after a few days. Tire pressure drops as outside temperatures drop, so tires bought in fall need regular checks into winter [8].
Tires for fleets and work vehicles
Commercial vehicles covered by federal motor carrier rules face their own tire limits [7]:
- Front steering tires need at least 4/32 of an inch of tread, and other tires at least 2/32 [7].
- No tire may carry more weight than its sidewall marking allows [7].
- Buses may not use regrooved, recapped or retreaded tires on the front wheels [7].
- Tires labeled for 55 mph or less may not be driven faster than that rating [7].
Good fleet practice goes further. Keep a tire specification sheet for each vehicle type. Check date codes when tires arrive, not after mounting. Record each TIN so a recall notice can be matched to the right vehicle. Passenger vans need extra care. See our 15 passenger van safety guide.
Frequently asked questions
Do I have to replace all four tires at once?
Not always. Check your owner’s manual first, since it may set rules for replacing fewer than four, especially on all wheel drive vehicles. If you replace two, match the size, type, load index and speed symbol of the tires staying on. Ask the installer which axle the new pair should go on and why.
Can I put a different tire size on my vehicle?
Only if the vehicle maker recommends it. NHTSA advises buying the original size or another size the maker recommends [1]. Approved sizes appear on the door label and in the owner’s manual [2]. If a seller suggests a different size, ask them to show you where the vehicle maker approves it.
How old is too old for a tire?
There is no single number for every vehicle. Some vehicle and tire makers advise replacing tires at 6 to 10 years, no matter the tread [1]. Check your owner’s manual for your vehicle’s advice. Read the date code on each tire, including the spare. If a tire is near that range, plan to replace it even if the tread looks good.
Is it safe to choose a higher load index or speed rating?
A higher load index or speed symbol keeps the margin the original tires had, as long as the size is right. Going lower is the risk. The federal standard requires the vehicle’s maximum load on each tire to stay within that tire’s rating [2]. If unsure, ask the installer to confirm the tire suits your vehicle and its recommended pressures.
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Safety Behind the Wheel Foundation recommends choosing replacement tires by your vehicle’s label and manual, not by price. A suitable replacement tire matches what your vehicle was built to carry, at the speeds and in the weather you really drive. Start with the door label and the owner’s manual. Match the size, then meet or beat the load index and speed symbol. Check the date code, pick a type for your worst weather, and register every tire.
Those few minutes of checking protect the four small patches of rubber that hold your family to the road. If a quote does not match your vehicle’s label, pause and ask before the tires go on.
Related articles
- Vehicle maintenance for safety: tires, brakes, lights and warning signs
- Driving in rain: hydroplaning, standing water and flood safety
- Driving in snow and ice: grip, black ice, skids and when to stay home
- Vehicle recalls and safety defects: how to check, fix and report
- Car emergencies while driving: blowouts, brake failure and skids
Sources and further reading
- 1National Highway Traffic Safety Administration (NHTSA). Tire Safety Ratings and Awareness (TireWise). Page undated; reviewed October 2026. Data year: 2024 (tire-related deaths); other content n/a (guidance). nhtsa.gov/vehicle-safety/tires
- 2Electronic Code of Federal Regulations. 49 CFR 571.110, Standard No. 110; Tire selection and rims and motor home/recreation vehicle trailer load carrying capacity information. Up to date as of October 1, 2026. ecfr.gov/…/section-571.110
- 3NHTSA. Tire Buyers’ FAQ: What You Should Know and Ask. Consumer handout, 2008. nhtsa.gov/node/35301
- 4Electronic Code of Federal Regulations. 49 CFR 571.139, Standard No. 139; New pneumatic radial tires for light vehicles. Up to date as of October 1, 2026. ecfr.gov/…/section-571.139
- 5NHTSA. Congratulations on Your New Tire Purchase. Consumer handout, 2014. nhtsa.gov/node/35306
- 6National Transportation Safety Board. Selected Issues in Passenger Vehicle Tire Safety. Special Investigation Report NTSB/SIR-15/02. Adopted October 27, 2015. Data year: 2009 to 2013 (recall completion); crashes investigated occurred in 2014. ntsb.gov/…/SIR1502.pdf
- 7Electronic Code of Federal Regulations (Federal Motor Carrier Safety Administration rules). 49 CFR 393.75, Tires. Up to date as of October 2, 2026. ecfr.gov/…/section-393.75
- 8NHTSA. Winter Weather Driving Tips: Prepare Your Vehicle. Page undated; reviewed October 2026. nhtsa.gov/winter-driving-tips
- 9Electronic Code of Federal Regulations. 49 CFR 575.6, Requirements (consumer information, including owner’s manual tire safety information). Up to date as of October 1, 2026. ecfr.gov/…/section-575.6
- 10Electronic Code of Federal Regulations. 49 CFR 575.104, Uniform tire quality grading standards. Up to date as of September 30, 2026. ecfr.gov/…/section-575.104
- 11Electronic Code of Federal Regulations. 49 CFR Part 574, Tire Identification and Recordkeeping. Up to date as of October 1, 2026. ecfr.gov/…/part-574
- 12NHTSA. Check for Recalls: Vehicle, Car Seat, Tire, Equipment. Page undated; reviewed October 2026. nhtsa.gov/recalls
This article reflects the safety priorities of tire care and everyday vehicle maintenance. It is general education, not legal, insurance or individual technical advice. Tire rules and recall details change, so verify them with official sources. For your own vehicle, check the owner's manual and door label, and talk with a qualified tire professional or the vehicle maker before changing tire size or type. Report tire safety problems to NHTSA. Reviewed October 2026.
Cite this article: Safety Behind the Wheel Foundation. “Choosing replacement tires: how to match size, load, speed rating, age and type.” drivewithcare.org, https://drivewithcare.org/choosing-replacement-tires/. Reviewed October 2026.
Special thanks to our contributors
We appreciate the professionals, experts, and community members who share their knowledge and perspectives to help make this resource better. Your insights are always welcome and appreciated.
Have professional expertise, firsthand experience, or a perspective that could make this resource better?
We welcome your input. Your knowledge and experience can help us make this resource more useful, accurate, and meaningful to the people who rely on it.
Thank you. Your contribution is on its way.
We’re grateful you took the time to share your knowledge with us. Our team reviews every contribution with care. If it helps improve this resource, we’ll update the page and recognize you the way you chose.
Keep learning
Safe Driving Resource Center
Guides, self-checks and articles for drivers, parents of new drivers, and families recovering after a crash.
