Miata Tire Size Calculator
Covers NA, NB, NC, and ND MX-5s — decode any tire code, compare an upgrade against stock, and check fender clearance before you order.
Quick Answer
ND MX-5 stock 205/45R17 = 24.32″ diameter. Swapping to 215/45R17 (+1.65%) is the most popular bolt-on upgrade — no fender modification. NC go-to: 225/45R17 on 17×8 ET45 (25.00″, +1.9%) fits without body mods. NC uses 5×114.3; NA, NB, and ND all use 4×100 — wheel generations are not interchangeable without adapters.
| Gen | OEM Size | Diameter | Bolt Pattern |
|---|---|---|---|
| NA (1989–1997) Base | 185/60R14 | 23.70″ | 4×100 |
| NB (1999–2005) Mazdaspeed | 205/45R16 | 23.99″ | 4×100 |
| NC (2006–2015) Grand Touring | 205/45R17 | 24.32″ | 5×114.3 |
| NC (2006–2015) Mazdaspeed | 215/40R18 | 24.42″ | 5×114.3 |
| ND (2016+) Sport 16″ | 195/50R16 | 23.56″ | 4×100 |
| ND (2016+) Club/GT 17″ | 205/45R17 | 24.32″ | 4×100 |
Max bolt-on width: ND 215mm, NC 225mm, NA/NB 205mm. NC wheels are NOT compatible with NA/NB/ND without adapters.
Miata common sizes — quick load:
NA MX-5
1989–1997Bolt: 4×100
NB MX-5
1999–2005Bolt: 4×100
NC MX-5
2006–2015Bolt: 5×114.3
ND MX-5
2016–presentBolt: 4×100
How to Use This Calculator
- 1Select your generation. Choose NA (1989–1997), NB (1998–2005), NC (2006–2015), or ND (2016–present) to load OEM stock sizes and bolt pattern data.
- 2Decode your current size. Enter your existing tire code (e.g. 205/45R17) in the Decode Size tab to see diameter, sidewall height, circumference, and revs per mile.
- 3Compare stock vs upgrade. On the Compare Sizes tab, enter your stock size in field A and the proposed new size in field B. The calculator shows speedometer error, diameter delta, and a fender clearance estimate.
- 4Check generation fitment. Use the Gen Fitment tab to confirm whether your proposed width and offset combo clears the fenders on your specific generation without rubbing.
- 5Find track compounds. The Track Tire tab lists recommended R-compound and performance street tires for each Miata generation and popular wheel size combination.
Miata Tire Sizing — Generation-by-Generation Guide
NC bolt pattern is incompatible with all other generations. The NC MX-5 (2006–2015) uses 5×114.3 — shared with the Mazda6 and most Japanese sedans. NA, NB, and ND use 4×100. This is the most critical fact when shopping for used Miata wheels.
15-inch track wheels remain the gold standard for NA/NB. On 15×8 ET25, the NA/NB chassis accepts 205/50R15 bolt-on, and 225/45R15 on 15×9 ET35 with fender rolling. The 15-inch selection in performance compounds (Hoosier SM7, Yokohama A048) remains far wider than 16″ or 17″ at comparable price points.
ND maximum width is 215mm before rubbing. The ND's tighter wheel wells limit bolt-on width to 215/45R17 on stock suspension. Moving to 225/45R17 requires either fender rolling, aftermarket flares, or lowered suspension at most offsets.
Offset range: ET25 to ET45 for all generations. A lower offset (ET25–ET30) maximizes track width and gives a more aggressive stance — but requires fender clearance confirmation. Above ET45, track width narrows and inner suspension clearance can become a concern on lowered builds.