Your tire sidewall shows size, type, load index, speed rating, and date code, so one quick read tells you what’s on your car.
You do not need a shop visit to figure out what kind of tires are on your car. Most of the answer is molded into the sidewall. Once you know where to look, you can spot the tire type, the size, the load rating, the speed rating, and the week and year it was made.
Read the tire in layers. Start with the full size string, then move to the symbols and the DOT code. Last, match what you see against the sticker on the driver’s door jamb so you know whether the set on the car matches what the vehicle was built to use.
How To Tell What Kind Of Tires You Have From One Sidewall Reading
Find the largest block of letters and numbers on the sidewall. It will look close to P225/65R17 102H, LT265/70R18, or 235/45R18 98W. That one line gives you the fastest read on the tire’s job and fit.
Read it from left to right:
- P means passenger tire.
- LT means light truck tire.
- ST means special trailer tire.
- T often marks a temporary spare.
- 225 is the section width in millimeters.
- 65 is the aspect ratio, or sidewall height compared with width.
- R means radial construction.
- 17 is the wheel diameter in inches.
- 102 is the load index.
- H is the speed rating.
If the size starts with no letter, many times you are looking at a Euro-metric tire. The rest of the code is still read in the same order.
Read The Service Type Before Anything Else
The first letter narrows the field fast. Passenger tires fit most daily-driven cars and many crossovers. Light truck tires are built for heavier loads and tougher use. Trailer tires are for trailer axles only. A temporary spare is for short-term emergency use. That is why a tire that looks close in size can still be the wrong pick for the vehicle.
Use The Symbols To Spot The Tire Category
After the size string, scan the rest of the sidewall for plain-language clues. You may see All Season, M+S, 3PMSF, A/T, M/T, Run Flat, Extra Load, or Touring. Michelin’s guide to tire sidewall markings shows the same sidewall language and where each marking sits.
- All Season points to a do-most-things road tire for mild year-round use.
- M+S is common on all-season and all-terrain tires.
- 3PMSF marks a tire that meets a winter traction test.
- A/T means all-terrain.
- M/T means mud-terrain.
- Run Flat marks a tire built to keep rolling for a limited distance after pressure loss on compatible vehicles.
- XL means Extra Load.
Do Not Skip The Load And Speed Marks
The last part of the size string matters just as much as the first. A 102H tire and a 102V tire can fit the same wheel, yet they are not the same class. The number is the load index. The letter is the speed rating. When you replace one tire, those marks help you avoid buying a tire that fits the rim but does not match the rest of the set.
| Sidewall Marking | What It Means | What It Tells You |
|---|---|---|
| P | Passenger tire | Built for cars, many crossovers, and lighter daily-duty use |
| LT | Light truck tire | Built for heavier loads, towing, work use, and tougher casings |
| ST | Special trailer tire | Made for trailer axles, not for a car or pickup steering axle |
| T | Temporary spare | Short-term spare with tighter speed and distance limits |
| 225/65R17 | Width, aspect ratio, construction, wheel size | Shows the tire’s physical fit |
| 102H | Load index and speed rating | Shows weight capacity and speed class |
| M+S or 3PMSF | Snow-related markings | Shows whether the tire has mud-and-snow labeling or a winter test symbol |
| DOT 3524 | Made in week 35 of 2024 | Shows tire age for matching sets and recall checks |
Match The Markings To The Way The Tire Is Built To Work
Once you have the code and symbols, you can sort the tire into a real-world group. A passenger all-season tire is the default on many sedans and family SUVs. A summer tire often has a higher speed rating and a tread built for warm pavement and wet grip, not snow. A winter tire will often show the 3PMSF symbol and deeper siping. An all-terrain tire often carries A/T in the name, plus chunkier shoulder blocks.
Run-flat tires need extra care when you identify them. The sidewall may say Run Flat, RFT, SSR, EMT, ROF, ZP, or another maker tag. If your car was built for run-flats, switching to a standard tire is not always a straight swap.
Check The DOT Code For Tire Age
Near the rim, you will find the DOT code. The NHTSA TireWise tire labeling page lays out the rating and labeling items found on passenger tires sold in the United States. The last four digits give the week and year of production. A code ending in 3524 means the tire was made in the 35th week of 2024. This does not tell you the tire type by itself, yet it helps you spot an older tire, a mismatched replacement, or one that may fall under a recall notice.
Age should not be your only filter. Tread depth, cracks, bulges, puncture history, and uneven wear still matter. Still, the date code is handy when one tire looks newer than the other three.
Read The Door Jamb Sticker Before You Buy Anything
The driver’s door jamb sticker is your reality check. It lists the tire size and cold inflation pressure the vehicle was set up to use. If the tire sidewall and the placard do not match, the fitment may not be what the vehicle maker chose for load, clearance, speed, and ride.
This sticker also helps when the brand name sounds sporty yet the sidewall shows an all-season touring tire in a standard passenger size. The label on the car cuts through that guesswork.
| Tire Kind | Easy Clues On The Tire | Typical Use |
|---|---|---|
| Passenger All-Season | P-metric or Euro-metric size, All Season, M+S | Daily commuting and mixed weather road use |
| Summer | Higher speed rating, no winter symbol, sportier tread | Warm-weather grip and sharper road feel |
| Winter | 3PMSF symbol, dense siping, soft cold-weather compound | Snow, slush, and colder road temps |
| All-Terrain | A/T in model name, blockier tread, often LT or XL | Pavement plus gravel, dirt, and light trail use |
| Mud-Terrain | M/T marking, wide voids, tougher off-road pattern | Loose mud, rocks, and rough off-road use |
| Run-Flat | Run Flat or maker code such as RFT or SSR | Limited driving after air loss on compatible vehicles |
| Temporary Spare | T-marked size, narrow tire, compact wheel | Short-term emergency use only |
What To Check When The Four Tires Do Not Match
Do not stop at one tire. Walk around the car and read all four. You may find the front and rear axle use different sizes on a staggered setup. You may also spot one newer replacement tire with a different speed rating, load index, or tread family.
If one tire has a different date code or a different model name, write down the full sidewall string from each corner. That gives you a clean list to compare before you order anything. It also helps a tire shop tell you whether you have a matched set, a mixed pair, or one odd tire that should not stay in service with the rest.
A Five-Minute Check At Home
If you want a fast answer without decoding every mark, use this order:
- Read the full size string on one tire.
- Check the first letter for P, LT, ST, or T.
- Look for All Season, M+S, 3PMSF, A/T, M/T, or Run Flat wording.
- Read the last four digits of the DOT code.
- Match the size to the driver’s door jamb sticker.
- Repeat on the other three tires.
Once you do that, you will know whether you have passenger, truck, trailer, winter, summer, all-terrain, run-flat, or spare tires, plus whether the set matches across the car. That makes the next step far easier and far less likely to go wrong.
References & Sources
- NHTSA.“Tire Safety Ratings and Awareness | TireWise | NHTSA.”Lists the sidewall rating and labeling items used to identify passenger tires in the United States.
- Michelin.“How to Read Tire Markings and Sidewall Codes – Michelin USA.”Shows where to find size, load index, speed rating, winter symbols, and other sidewall markings.