2021 Subaru WRX — Premium
The 2021 Subaru WRX Premium came from the factory equipped with 245/40R18 tires. If your vehicle has since been fitted with aftermarket or upsized wheels, your actual tire size may no longer match this factory spec — always confirm against your door placard before buying.
245/40R18
| Section width | 245 mm |
|---|---|
| Aspect ratio (sidewall height) | 40% (98 mm) |
| Rim diameter | 18" |
| Overall tire diameter | ~25.7" |
| Revolutions per mile | ~784 |
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What this size means for your Subaru WRX
On the 2021 Subaru WRX Premium, the factory 245/40R18 measures about 25.7″ in overall diameter with a 98 mm (3.9″) sidewall, and completes roughly 784 revolutions per mile. Its 40-series aspect ratio gives a low-profile sidewall tuned for sharper handling, common on sport trims and larger-wheel packages. In tire terms it is a passenger (P-metric / Euro-metric) size.
Other 2021 Subaru WRX trims
- Limited 245/40R18
- Standard 235/45R17
- STI 245/35R19
- STI Limited 245/35R19
Subaru WRX tire sizes by year
- 2025 Subaru WRX 245/40R18
- 2024 Subaru WRX 235/45R17
- 2023 Subaru WRX 235/45R17
- 2022 Subaru WRX 235/45R17
- 2020 Subaru WRX 245/40R18
- 2019 Subaru WRX 245/40R18
- 2018 Subaru WRX 245/40R18
- 2017 Subaru WRX 245/40R18
- 2016 Subaru WRX 245/40R18
- 2015 Subaru WRX 235/45R17
How to read a tire size
A tire size like 225/45R17 breaks down into three parts:
the first number is the section width in millimeters
(the tire's width from sidewall to sidewall), the second is the
aspect ratio — the sidewall's height as a percentage of
that width — and the number after the "R" is the rim
diameter in inches. A letter prefix (P or LT) indicates
Passenger or Light Truck construction; its absence usually means
Euro-metric sizing.
Some trucks and off-road tires instead use "flotation" sizing, like
37X12.50R17 — here the numbers are the tire's overall
diameter and width in inches directly, with the rim diameter last.
Always verify against the tire information placard on your driver's-side door jamb or your owner's manual before purchasing — tire size can vary by factory option package even within the same trim.