TireSizeCalc

265/70R17 vs 275/70R17

275/70R17 is +0.55 in (+1.7%) in diameter and 0.39 in wider than 265/70R17.

Size comparison265/70R17
Dimension265/70R17 275/70R17Difference
Overall diameter
UN R30 §6.1.2.1
31.61 in 802.8 mm32.16 in 816.8 mm+0.55 in
Section width
UN R30 §6.1.2.1
10.43 in 265.0 mm10.83 in 275.0 mm+0.40 in
Sidewall height
UN R30 §6.1.2.1
7.30 in 185.5 mm7.58 in 192.5 mm+0.28 in
Rim diameter
Marked on the tire
17 in17 in0 in
Circum­ference
From diameter
99.29 in101.03 in+1.74 in
Revolutions per mile
From diameter
638627−11
Allowed real diameter
UN R30 §6.1.5
31.17–32.19 in31.70–32.76 in
Nominal, not measuredReal tires vary by brand and load range.
31.61 in
  • 265/70R17 31.61 in
  • 275/70R17 32.16 in
Drawn to scale on one ground line.

Speedometer change

mphTrue speed 61.0 mph (+1.0 mph)

If your speedometer is calibrated for 265/70R17 and you fit 275/70R17, the tire is +1.7% in diameter, so your true speed differs from the reading as shown below.

Speedometer reading versus true speed
ReadingTrue speedDifference
30 mph30.5 mph+0.5 mph
45 mph45.8 mph+0.8 mph
55 mph56.0 mph+1.0 mph
60 mph61.0 mph+1.0 mph
70 mph71.2 mph+1.2 mph
80 mph81.4 mph+1.4 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.