305/30R20 tires: size explained
305/30R20 is a Euro-metric tire size. It is about 27.2 in (691 mm) tall, 305 mm wide, and made for a 20-inch wheel.
What 305/30R20 means
A tire size describes the tire's shape and the wheel it fits. It says nothing about load capacity or speed capability, which are printed separately on the sidewall.
- No letterEuro-metric
- With no letter in front of the width, this is a Euro-metric size (also called hard metric). It has the same dimensions as the P-metric version but is built to a different load standard, so its load capacity can differ.
- 305Section width
- The tire's width is 305 millimeters (12.0 in), measured from sidewall to sidewall.
- 30Aspect ratio
- The sidewall height is 30% of the width. For 305 mm that is about 3.6 in (92 mm). A smaller number means a shorter sidewall.
- RRadial construction
- R means radial construction, where the internal cords run across the tire from one edge to the other.
- 20Wheel (rim) diameter
- The tire is made for a wheel 20 inches across. Its overall diameter is larger: about 27.2 in (691 mm).
305/30R20 dimensions
- Section width
- 12.0 in (305 mm)
- Sidewall height
- 3.6 in (92 mm)
- Wheel (rim) diameter
- 20.0 in (508 mm)
- Overall diameter
- 27.2 in (691 mm)
- Circumference
- 85.5 in (2171 mm)
- Revolutions per mile
- 741
These are nominal design dimensions. Real tires vary by brand, tread depth, wheel width, load and pressure.
Which vehicles use 305/30R20?
These vehicles list 305/30R20 among their verified sizes, by trim. Open one to see all of its sizes.
- 2022 Acura NSX Type S(rear)
- 2021 Acura NSX NSX(rear)
- 2020 Acura NSX NSX(rear)
- 2026 Chevrolet Corvette Stingray(rear)
- 2025 Chevrolet Corvette Stingray 1LT(rear)
- 2025 Chevrolet Corvette Stingray 1LT w/ Z51 Performance Pkg.(rear)
- 2025 Chevrolet Corvette Stingray 2LT(rear)
- 2025 Chevrolet Corvette Stingray 2LT w/ Z51 Performance Pkg.(rear)
- 2025 Chevrolet Corvette Stingray 3LT(rear)
- 2025 Chevrolet Corvette Stingray 3LT w/ Z51 Performance Pkg.(rear)
Shop for 305/30R20 tires
Confirm the size on your tire sidewall or door placard first. These links open each store's own search for 305/30R20; prices and stock are on their sites.
- Search 305/30R20 at Tire Rack
- Search 305/30R20 at Discount Tire
- Search 305/30R20 at SimpleTire
- Search 305/30R20 at Amazon
- Search 305/30R20 at Priority Tire
We may earn a commission if you buy through these links. It doesn't change the price you pay. Read our affiliate disclosure.
Snow chains and tire socks for 305/30R20
Where winter roads call for extra traction, chains and tire socks are two options that fit over your tires. They are made for specific tire sizes, so these links open Amazon searches for 305/30R20. Whether they suit your vehicle depends on its clearance and the local rules.
Paid links to Amazon search results. As an Amazon Associate I earn from qualifying purchases. Read our affiliate disclosure.
Before you buy
- Chains and socks are sold by tire size, so match the size on your sidewall exactly.
- Check your owner's manual first: many newer cars and SUVs limit or prohibit chains, or require low-profile (often called SAE Class S) chains because of tight wheel-well clearance.
- Tire socks are a lighter-duty option; check your state's rules, because some areas only accept chains when chain controls are in effect.
- Put them on the drive wheels (or as your manual says) and follow the maker's speed limit.
Similar sizes
These common sizes have an overall diameter within about 3% of 305/30R20. A common rule of thumb is to keep a replacement size within about 3% of the original overall diameter. Confirm any size change with your vehicle's owner's manual or a tire professional.
| Size | Wheel diameter | Diameter difference | Calculator |
|---|---|---|---|
| 215/65R16 | 16 in (different) | -0.74% | Compare 305/30R20 with 215/65R16 |
| 225/60R17 | 17 in (different) | +1.56% | Compare 305/30R20 with 225/60R17 |
| 225/55R17 | 17 in (different) | -1.69% | Compare 305/30R20 with 225/55R17 |
| 245/40R19 | 19 in (different) | -1.79% | Compare 305/30R20 with 245/40R19 |
| 245/45R18 | 18 in (different) | -1.92% | Compare 305/30R20 with 245/45R18 |
| 225/60R16 | 16 in (different) | -2.11% | Compare 305/30R20 with 225/60R16 |
Same dimensions, different load standard
P305/30R20 (P-metric) has the same dimensions as 305/30R20, but it is built to a different load standard. Check the load index on the sidewall rather than assuming the two are interchangeable.
Compare 305/30R20 with similar sizes
Side-by-side dimensions and speedometer difference for sizes close to 305/30R20 in overall diameter.
- 235/50R18 vs 305/30R20+0.17% taller than 305/30R20
- 215/60R17 vs 305/30R20-0.17% shorter than 305/30R20
- 265/35R20 vs 305/30R20+0.36% taller than 305/30R20
- 205/75R15 vs 305/30R20-0.36% shorter than 305/30R20
- 235/60R16 vs 305/30R20-0.38% shorter than 305/30R20
- 215/55R18 vs 305/30R20+0.39% taller than 305/30R20
- 235/45R19 vs 305/30R20+0.45% taller than 305/30R20
- 265/40R19 vs 305/30R20+0.52% taller than 305/30R20
- 255/40R19 vs 305/30R20-0.64% shorter than 305/30R20
- 225/45R19 vs 305/30R20-0.85% shorter than 305/30R20
Compare 305/30R20 with another size
See how another size differs in height, width, sidewall and speedometer reading in the tire size calculator.
Compare 305/30R20 with another sizeQuestions about 305/30R20
What does 305/30R20 mean?
305/30R20 describes the shape and size of a tire, not how much it can carry or how fast it can go. 305 is the width in millimeters, 30 is the sidewall height as a percentage of that width (about 92 mm), R is the construction type and 20 is the wheel diameter in inches.
How tall is a 305/30R20 tire?
A 305/30R20 tire has a nominal overall diameter of about 27.2 in (691 mm), with a sidewall about 3.6 in (92 mm) tall. These are nominal design dimensions. Real tires vary by brand, tread depth, wheel width, load and pressure.
How many revolutions per mile does a 305/30R20 tire make?
About 741 revolutions per mile, based on a circumference of 85.5 in (2171 mm). A vehicle's speedometer and odometer are calibrated to the tire size it was built with, so a size with a different overall diameter changes what they read. A common rule of thumb is to keep a replacement size within about 3% of the original overall diameter. Confirm any size change with your vehicle's owner's manual or a tire professional.
Is 305/30R20 the same as P305/30R20?
They have the same dimensions: both are about 27.2 in (691 mm) tall and 305 mm wide. They are built to different load standards, though (Euro-metric and P-metric), so the load a tire can carry can differ. Check the load index on the sidewall, and ask a tire professional or your owner's manual before treating them as interchangeable.
Which sizes have a similar diameter to 305/30R20?
Among the common sizes we list, these are within about 3% of the overall diameter of 305/30R20: 215/65R16 (-0.74%), 225/60R17 (+1.56%), 225/55R17 (-1.69%), and 3 more. Diameter is only one measure. Width, wheel diameter, load capacity and clearance matter too. Confirm any size change with your vehicle's owner's manual or a tire professional.
You might also need
- Digital tire pressure gauge (Amazon search, opens in a new tab)
Check your tire pressure against the number on your door placard.
- Portable tire inflator (Amazon search, opens in a new tab)
Top up a low tire at home without a trip to the gas station.
- Tire tread depth gauge (Amazon search, opens in a new tab)
Measure how much tread is left before you decide to replace.
- Lug wrench or torque wrench (Amazon search, opens in a new tab)
Useful for rotations and tire changes; follow the torque spec in your owner's manual.
Paid links to Amazon search results. As an Amazon Associate I earn from qualifying purchases. Read our affiliate disclosure.