Plus-Two Tire Calculator
Find Plus-Two tire sizes for wheels two inches larger than stock. Compare overall diameter and the sidewall height lost with each size.
Compare sizes using two-inch wheel increases.
Plus-Two Tire Calculator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Plus-Two Tire Calculator Works?
The Plus-Two Tire Calculator works by adding 2 inches (50.8 mm) to the rim diameter and finding the lower-profile size that keeps the overall diameter closest to stock. The calculation has 4 steps.
Enter the stock size
Type the factory size, for example 225/45 R17.
Add two inches
The calculator sets the new rim to 19 in, adding 50.8 mm to the bead seat diameter.
Cut the sidewall
The calculator removes 25.4 mm (1.0 in) from each sidewall to hold the diameter.
Match a real size
The calculator tests widths up to 20 mm wider and returns the closest size, such as 245/30 R19 for a 225/45 R17 stock tire.
Plus-Two Tire Calculator Formula
The Plus-Two Tire Calculator formula is SH₂ = SH₀ − 25.4 mm, and AR₂ = SH₂ ÷ W₂ × 100.
Rim₂ = Rim₀ + 2SH₂ = SH₀ − 25.4AR₂ = SH₂ ÷ W₂ × 100Loss% = 25.4 ÷ SH₀ × 100- SH₀
- Stock sidewall height (mm)
- SH₂
- Plus-Two sidewall height (mm)
- W₂
- Plus-Two width (mm)
Worked example
A 205/55 R16 tire has a 112.75 mm sidewall. A Plus-Two size needs about 87.4 mm on an 18-inch wheel, a 22.5% sidewall loss. On a 215 mm width, the aspect ratio is 40.7%, so the match is 215/40 R18 at 629.2 mm (-0.43%).
Plus-Two Tire Calculator Conversion Table
The Plus-Two Tire Calculator conversion table lists the closest Plus-Two size for 7 common stock sizes.
| Stock size | Plus-Two size | Diameter change | Gap | Sidewall change |
|---|---|---|---|---|
| 195/65 R15 | 205/50 R17 | 634.5 → 636.8 mm | +0.36% | 126.8 → 102.5 mm |
| 205/55 R16 | 215/40 R18 | 631.9 → 629.2 mm | -0.43% | 112.8 → 86.0 mm |
| 215/60 R16 | 235/45 R18 | 664.4 → 668.7 mm | +0.65% | 129.0 → 105.8 mm |
| 225/45 R17 | 245/30 R19 | 634.3 → 629.6 mm | -0.74% | 101.2 → 73.5 mm |
| 235/45 R18 | 235/35 R20 | 668.7 → 672.5 mm | +0.57% | 105.8 → 82.2 mm |
| 245/40 R18 | 245/30 R20 | 653.2 → 655.0 mm | +0.28% | 98.0 → 73.5 mm |
| 225/65 R17 | 245/50 R19 | 724.3 → 727.6 mm | +0.46% | 146.2 → 122.5 mm |
What is Plus-Two Tire Calculator?
A Plus-Two Tire Calculator is a tool that finds a tire size for a wheel 2 inches larger than stock while holding the overall diameter. Plus-Two changes are popular for appearance and for clearing large brake calipers.
A Plus-Two change removes about 25.4 mm (1.0 in) of sidewall, which is 20% to 30% of a typical passenger sidewall. Ride firmness, road noise and pothole damage risk rise in a way most drivers notice.
Plus-Two packages often weigh more than stock. A heavier wheel and tire raises unsprung mass and slows acceleration.
What are the uses of Plus-Two Tire Calculator?
There are 4 main uses of the Plus-Two Tire Calculator, including appearance packages and big brake clearance.
Appearance packages
Pick tires for a 2-inch larger custom wheel.
Big brake clearance
Fit wheels large enough for 6-piston calipers.
Ride trade-off checks
See the full sidewall loss before committing to a large wheel.
Track setups
Reduce sidewall flex for consistent lap times.
Related Wheel Sizing & Conversion Tools
View All 134 Subtools →Find sizes near a target diameter.
Solve for nominal aspect ratio.
Filter candidates using specified limits.
Compare alternatives on one rim diameter.
Compare sizes using larger wheels.
Explore specified wheel diameter increases.