# 305/40 R20

## What size is 305/40 R20?

305/40 R20 has an overall diameter of about 29.61 in, a section width of 12.01 in and a sidewall height of 4.80 in. It turns roughly 681 times per mile. Below are the exact figures plus in-tolerance plus/minus sizes you can switch to safely.

## Specification

| Specification | |
|---|---|
| Overall diameter | 29.61 in |
| Section width | 12.01 in |
| Sidewall height | 4.80 in |
| Circumference | 93.01 in |
| Revolutions | 423 /km · 681 /mi |

## In-tolerance sizes

| Size | Diameter | Speedo | Verdict |
|---|---|---|---|
| [245/60 R18](https://tirefitlab.com/245-60-r18.md) | -0.1% | -0.1% | ✓ OK |
| [245/65 R17](https://tirefitlab.com/245-65-r17.md) | -0.2% | -0.2% | ✓ OK |
| [245/70 R16](https://tirefitlab.com/245-70-r16.md) | -0.3% | -0.3% | ✓ OK |
| [275/45 R20](https://tirefitlab.com/275-45-r20.md) | +0.5% | +0.5% | ✓ OK |
| [265/50 R19](https://tirefitlab.com/265-50-r19.md) | -0.6% | -0.6% | ✓ OK |
| [265/45 R20](https://tirefitlab.com/265-45-r20.md) | -0.7% | -0.7% | ✓ OK |
| [285/35 R22](https://tirefitlab.com/285-35-r22.md) | +0.8% | +0.8% | ✓ OK |
| [295/40 R20](https://tirefitlab.com/295-40-r20.md) | -1.1% | -1.1% | ✓ OK |
| [235/70 R17](https://tirefitlab.com/235-70-r17.md) | +1.2% | +1.2% | ✓ OK |
| [235/65 R18](https://tirefitlab.com/235-65-r18.md) | +1.4% | +1.4% | ✓ OK |
| [235/55 R19](https://tirefitlab.com/235-55-r19.md) | -1.4% | -1.4% | ✓ OK |
| [255/50 R20](https://tirefitlab.com/255-50-r20.md) | +1.5% | +1.5% | ✓ OK |

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Methodology: https://tirefitlab.com/methodology/ · Tire size calculator: https://tirefitlab.com/305-40-r20/

> Geometry is computed in canonical millimetres and is deterministic across the site. Always verify physical clearance before fitting.