I know this is a lot if info, but here it is.

Logansportage <img src="/forums/images/graemlins/patriot.gif" alt="" />

Dimensions

Dimension Tire A: 205/75 R 15 (27 x 8.07 x 15)
Width 8.07" 205.00mm)
Sidewall height 6.05" (153.75mm)
Overall height 27.11" (688.50mm)
Circumference 85.16" (2162.99mm)

Dimension Tire B: 267/76 R 15 (31 x 10.51 x 15)
Width 10.51" (267.00mm)
Sidewall height 7.99" (202.92mm)
Overall height 30.98" (786.84mm)
Circumference 97.32" (2471.93mm)

Difference
Width +2.44" (+62.00mm)
Sidewall height +1.94" (+49.17mm)
Overall height +3.87" (+98.34mm)
Circumference +12.16" (+308.94mm)

Speedometer Error

Actual Speed | Indicated Speed with Tire B | Speedometer Error
5 mph (8.04 kph) | 4.38 mph (7.04 kph) | -0.62 mph (-1.01 kph)
10 mph (16.09 kph) | 8.75 mph (14.08 kph) | -1.25 mph (-2.01 kph)
15 mph (24.13 kph) | 13.13 mph (21.12 kph) | -1.87 mph (-3.02 kph)
20 mph (32.18 kph) | 17.50 mph (28.16 kph) | -2.50 mph (-4.02 kph)
25 mph (40.23 kph) | 21.88 mph (35.20 kph) | -3.12 mph (-5.03 kph)
30 mph (48.27 kph) | 26.25 mph (42.24 kph) | -3.75 mph (-6.03 kph)
35 mph (56.31 kph) | 30.63 mph (49.28 kph) | -4.37 mph (-7.04 kph)
40 mph (64.36 kph) | 35.00 mph (56.32 kph) | -5.00 mph (-8.04 kph)
45 mph (72.41 kph) | 39.38 mph (63.36 kph) | -5.62 mph (-9.05 kph)
50 mph (80.45 kph) | 43.75 mph (70.40 kph) | -6.25 mph (-10.05 kph)
55 mph (88.50 kph) | 48.13 mph (77.43 kph) | -6.87 mph (-11.06 kph)
60 mph (96.54 kph) | 52.50 mph (84.47 kph) | -7.50 mph (-12.07 kph)
65 mph (104.58 kph) | 56.88 mph (91.51 kph) | -8.12 mph (-13.07 kph)
70 mph (112.63 kph) | 61.25 mph (98.55 kph) | -8.75 mph (-14.08 kph)
75 mph (120.67 kph) | 65.63 mph (105.59 kph) | -9.37 mph (-15.08 kph)
80 mph (128.72 kph) | 70.00 mph (112.63 kph) | -10.00 mph (-16.09 kph)
85 mph (136.76 kph) | 74.38 mph (119.67 kph) | -10.62 mph (-17.09 kph)
90 mph (144.81 kph) | 78.75 mph (126.71 kph) | -11.25 mph (-18.10 kph)
95 mph (152.85 kph) | 83.13 mph (133.75 kph) | -11.87 mph (-19.10 kph)
100 mph (160.90 kph) | 87.50 mph (140.79 kph) | -12.50 mph (-20.11 kph)
105 mph (168.94 kph) | 91.88 mph (147.83 kph) | -13.12 mph (-21.11 kph)
110 mph (176.99 kph) | 96.25 mph (154.87 kph) | -13.75 mph (-22.12 kph)
115 mph (185.03 kph) | 100.63 mph (161.91 kph) | -14.37 mph (-23.13 kph)
120 mph (193.08 kph) | 105.00 mph (168.95 kph) | -15.00 mph (-24.13 kph)
125 mph (201.12 kph) | 109.38 mph (175.99 kph) | -15.62 mph (-25.14 kph)
130 mph (209.17 kph) | 113.75 mph (183.03 kph) | -16.25 mph (-26.14 kph)
135 mph (217.22 kph) | 118.13 mph (190.07 kph) | -16.87 mph (-27.15 kph)
140 mph (225.26 kph) | 122.50 mph (197.11 kph) | -17.50 mph (-28.15 kph)
145 mph (233.31 kph) | 126.88 mph (204.15 kph) | -18.12 mph (-29.16 kph)
150 mph (241.35 kph) | 131.25 mph (211.19 kph) | -18.75 mph (-30.16 kph)
155 mph (249.40 kph) | 135.63 mph (218.23 kph) | -19.37 mph (-31.17 kph)
160 mph (257.44 kph) | 140.00 mph (225.26 kph) | -20.00 mph (-32.18 kph)
165 mph (265.49 kph) | 144.38 mph (232.30 kph) | -20.62 mph (-33.18 kph)
170 mph (273.53 kph) | 148.75 mph (239.34 kph) | -21.25 mph (-34.19 kph)
175 mph (281.57 kph) | 153.13 mph (246.38 kph) | -21.87 mph (-35.19 kph)
180 mph (289.62 kph) | 157.50 mph (253.42 kph) | -22.50 mph (-36.20 kph)
185 mph (297.67 kph) | 161.88 mph (260.46 kph) | -23.12 mph (-37.20 kph)
190 mph (305.71 kph) | 166.25 mph (267.50 kph) | -23.75 mph (-38.21 kph)
195 mph (313.75 kph) | 170.63 mph (274.54 kph) | -24.37 mph (-39.21 kph)
200 mph (321.80 kph) | 175.00 mph (281.58 kph) | -25.00 mph (-40.22 kph)

If your speedometer has been calibrated for 205/75 R 15 (27 x 8.07 x 15) tires, replacing them with 267/76 R 15's (31 x 10.51 x 15's) would result in the speedometer reading low by 12.50%.

Odometer Error

Actual Mileage | Indicated Mileage with Tire B | Odometer Error
1 mi (1.61 km) | 0.88 mi (1.41 km) | -0.12 mi (-0.20 km)
5 mi (8.04 km) | 4.38 mi (7.04 km) | -0.62 mi (-1.01 km)
10 mi (16.09 km) | 8.75 mi (14.08 km) | -1.25 mi (-2.01 km)
50 mi (80.45 km) | 43.75 mi (70.40 km) | -6.25 mi (-10.05 km)
100 mi (160.90 km) | 87.50 mi (140.79 km) | -12.50 mi (-20.11 km)
500 mi (804.50 km) | 437.51 mi (703.95 km) | -62.49 mi (-100.55 km)
1000 mi (1609.00 km) | 875.02 mi (1407.91 km) | -124.98 mi (-201.09 km)
5000 mi (8045.00 km) | 4375.10 mi (7039.53 km) | -624.90 mi (-1005.47 km)
10000 mi (16090.00 km) | 8750.19 mi (14079.06 km) | -1249.81 mi (-2010.94 km)
50000 mi (80450.00 km) | 43750.96 mi (70395.29 km) | -6249.04 mi (-10054.71 km)
100000 mi (160900.00 km) | 87501.91 mi (140790.58 km) | -12498.09 mi (-20109.42 km)

Same as with the speedometer, if your odometer has been calibrated for 205/75 R 15 (27 x 8.07 x 15) tires, replacing them with 267/76 R 15's (31 x 10.51 x 15's) would result in the odometer reading low by 12.50%.