The safest way to check tire size and fit for any passenger vehicle or light truck is to read the driver-side door-jamb placard — the manufacturer’s recommendation printed there always takes priority over the numbers on the current sidewall.
A single wrong tire size can nudge your speedometer off, upset the ABS, or rub fender liners on bumps. The fix isn’t guessing — it’s one door swing and a glance at the placard. Here’s the exact order to check, read, and verify tire fit, so you replace only what belongs on the car.
Where To Find Your Vehicle’s Correct Tire Size
The tire and loading placard inside the driver-side door jamb is the definitive source. Open the driver door and look for a white or silver sticker adhered to the door frame itself. It lists the recommended tire size, inflation pressure, and sometimes the load index and speed rating your car was designed for.
If the placard is missing or unreadable, check these secondary locations:
- Owner’s manual — will list the OEM tire size and speed rating alongside inflation guidelines.
- Inside the glove box door — some manufacturers place a duplicate sticker here.
- Fuel hatch door — on certain vehicles, a second sticker lives here.
- Vehicle documents (Certificate of Conformity) — lists approved sizes and alternatives.
- VIN-based lookup tool — a VIN decoder can give you the factory tire spec for your exact trim.
A common mistake is copying the sidewall size from a set of aftermarket tires that the previous owner bolted on. The placard overrules whatever is mounted today. If the two differ, go with the placard.
How To Read The Tire Size Code On The Sidewall
Once you’ve confirmed the correct size from the placard, you can verify what the current tires actually say. The code printed on every tire sidewall follows a standard format. Using the example 205/65R16 95W:
- 205 — section width in millimeters (tread width at its widest point).
- 65 — aspect ratio; sidewall height as a percentage of the width (here, 65% of 205 mm).
- R — radial construction, which is nearly universal on passenger cars.
- 16 — wheel diameter in inches.
- 95W — load index (95 = 1520 lbs per tire) and speed rating (W = 168 mph max).
Michelin’s guide to tire size codes walks through each number, plus the less-common letters for specialty tires. The load index and speed rating matter as much as the three-digit size code — never fit a tire with a lower load index or a slower speed rating than OEM.
Fit Checks Beyond The Printed Size
Matching the printed code is step one. Step two is confirming the new tire will actually clear the vehicle’s hardware. Here are the critical checks:
- Overall diameter should stay within ~3% of OEM to avoid speedometer error and ABS interference. A tire size calculator compares diameter, circumference, and revolutions per mile.
- Wheel width and offset must suit the new tire. A tire stretched onto a too-narrow rim or pinched on a too-wide rim handles poorly and wears unevenly.
- Brake caliper and fender clearance — larger tires can contact the caliper at full lock or rub the inner fender over bumps, especially on lowered cars.
- Load index — the replacement tire’s load rating must meet or exceed the OEM number. Dropping below is unsafe for weight limits.
If you’re shopping and want to keep the cost down without risking fitment, check our roundup of budget-friendly tire picks — each option is verified against common OEM sizes and clearance needs.
Common Mistakes That Lead To The Wrong Fit
Even experienced buyers make these errors. Skip them and your replacement will bolt on without drama:
- Copying the current sidewall when aftermarket tires are mounted instead of checking the placard — the most frequent mistake.
- Ignoring load index or speed rating and only comparing the 205/65R16 portion of the code.
- Changing overall diameter too much — a diameter shift over 3% can throw off the speedometer calibration by several mph.
- Confusing the size code with the DOT date code. The DOT digits, ending in a four-number week/year (e.g., “3423”), tell you when the tire was manufactured, not its size.
FAQs
Can I use a tire size that doesn’t match the placard?
Using a size not listed on the placard is possible only after you confirm clearance, wheel width, diameter change, and adequate load index. A mismatch that alters overall diameter by more than 3% will affect the speedometer and can interfere with traction control.
What if the tire placard is missing?
If the door jamb sticker is gone, check the owner’s manual, glove box sticker, or fuel hatch for a duplicate. As a last resort, look up your vehicle’s VIN using a dedicated fitment tool — it will return the factory-equipped tire size for your specific trim.
Is the speed rating on the sidewall mandatory?
Yes. The speed rating indicates the tire’s maximum safe sustained speed, and dropping below the OEM rating is unsafe. You can fit a tire with a higher speed rating if the size and clearance work, but never go lower.
References & Sources
- Michelin. “Find Your Tire Size.” Walks through sidewall code reading and placard location.
- Consumer Reports. “How to Decode Tire Size and Other Data.” Covers load index, speed rating, and common sizing pitfalls.
- Goodyear. “How to Find My Tire Size.” Explains where to locate the placard and how to read the sidewall code.