Tires
#2
CF Monarch
#3
#4
CF Monarch
I have listed the facts below so that you can decided what to do:
Diameter inches (mm) 30.47 (773.9)/27.1 (688.4) -3.37 (-85.5) -11%
Width inches (mm)9.65 (245)/ 9.25 (235)/-0.39 (-10) -4.1%
Circumference/ inches (mm) 95.72 (2431.28) 85.14 (2162.67) -10.58 (-268.61) -11%
Sidewall Height inches (mm)7.23 (183.75)5.55 (141)-1.68 (-42.75) -23.3%
Revolutions per mile (km)661.93 (411.31)744.15 (462.39)82.21 (51.08) 12.4%
Speedometer Difference
Speedo ReadingActual Speed20 mph (32.19 km/h)17.79 mph (28.63 km/h)
25 mph (40.23 km/h)22.24 mph (35.79 km/h)
30 mph (48.28 km/h)26.69 mph (42.95 km/h)
35 mph (56.33 km/h)31.13 mph (50.1 km/h)
40 mph (64.37 km/h)35.58 mph (57.26 km/h)
45 mph (72.42 km/h)40.03 mph (64.42 km/h)
50 mph (80.47 km/h)44.48 mph (71.58 km/h)
55 mph (88.51 km/h)48.92 mph (78.74 km/h)
60 mph (96.56 km/h)53.37 mph (85.89 km/h)
65 mph (104.61 km/h)57.82 mph (93.05 km/h)
Gear Ratio / RPMs for New Tire (@ 65 mph)
2.35 2.73 2.94 3.07 3.21 3.31 3.42 3.55 3.73 3.91 4.11 4.27 4.56 4.88 5.3 5.29 5.38 5.71 6.70 7.17 =Axle Gear Ratio
1894 2200 2369 2474 2587 2667 2756 2861 3006 3151 3312 3441 3675 3932 4134 4263 4335 4601 4972 5778 =Engine RPM's
Your vehicle will likely use more fuel with smaller tires, but the motor will rev up quicker as well. You will not reach the same top speed without going over red-line..
Snow and mud tires might be somewhat larger then these specifications, but not by much. They will be lighter by a small margin too. It may interfere with the ECM operation too.
Last edited by oilcanhenry; November 2nd, 2019 at 2:29 PM.
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oilcanhenry (November 2nd, 2019)
#6
CF Monarch
#7
Load/speed rating
The other thing to check on as well with trying to go down in tire size is the load/speed rating of the smaller tire and making sure it's still adequate for the express. 245s are usually considered light truck where as 235 can be either light truck or car
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