TireSizeCalc

275/55R20 vs 295/55R20

295/55R20 is +0.87 in (+2.7%) in diameter and 0.79 in wider than 275/55R20.

Size comparison275/55R20
Dimension275/55R20 295/55R20Difference
Overall diameter
UN R30 §6.1.2.1
31.91 in 810.5 mm32.78 in 832.5 mm+0.87 in
Section width
UN R30 §6.1.2.1
10.83 in 275.0 mm11.61 in 295.0 mm+0.78 in
Sidewall height
UN R30 §6.1.2.1
5.95 in 151.3 mm6.39 in 162.3 mm+0.44 in
Rim diameter
Marked on the tire
20 in20 in0 in
Circum­ference
From diameter
100.25 in102.97 in+2.72 in
Revolutions per mile
From diameter
632615−17
Allowed real diameter
UN R30 §6.1.5
31.55–32.39 in32.39–33.29 in
Nominal, not measuredReal tires vary by brand and load range.
31.91 in
  • 275/55R20 31.91 in
  • 295/55R20 32.78 in
Drawn to scale on one ground line.

Speedometer change

mphTrue speed 61.6 mph (+1.6 mph)

If your speedometer is calibrated for 275/55R20 and you fit 295/55R20, the tire is +2.7% in diameter, so your true speed differs from the reading as shown below.

Speedometer reading versus true speed
ReadingTrue speedDifference
30 mph30.8 mph+0.8 mph
45 mph46.2 mph+1.2 mph
55 mph56.5 mph+1.5 mph
60 mph61.6 mph+1.6 mph
70 mph71.9 mph+1.9 mph
80 mph82.2 mph+2.2 mph

What changes

Nominal dimensions from the official sizing formula (sources below). This comparison doesn't check fit: wheel width, offset and clearance decide that. See changing tire size.

Each size

Sources

  1. UN Regulation No. 30 - Uniform provisions concerning the approval of pneumatic tyres for motor vehicles and their trailers (Revision 3). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.29/Rev.3. 2007-03-29. Para 2.15 and 6.1.2.1: aspect ratio and outer diameter, D = d + 2H. Retrieved 2026-11-01.
  2. UN Regulation No. 54 - Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers (Revision 2). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.53/Rev.2. 2004-04-16. Para 6.1.2.1: the same formula for light truck tires. Retrieved 2026-11-01.
  3. UN Regulation No. 30 - Uniform provisions concerning the approval of pneumatic tyres for motor vehicles and their trailers (Revision 3). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.29/Rev.3. 2007-03-29. Para 6.1.5: allowed outer diameter, Dmin = d + 2H x 0.97, Dmax = d + 2H x 1.04. Retrieved 2026-11-01.
  4. Computed by tiresizecalc.net from the cited formula. Sri Murugan Systems. Circumference = pi x diameter; revolutions per mile = 63,360 / circumference; 1 in = 25.4 mm exactly. Retrieved 2026-11-01.
  5. Computed by tiresizecalc.net from the cited formula. Sri Murugan Systems. Speedometer: true speed = indicated speed x new diameter / old diameter. Retrieved 2026-11-01.

Last reviewed 2026-11-01. The full source list, with dates and file checksums, is in How the numbers are calculated. To report an error, email contactus@tiresizecalc.net.