Try using this tool
http://www.1010tires.com/tiresizecalculator.aspAccording to it, the size you are looking to go to is above the recommended maximum of 3% in difference in tire diameter.
Stock Tire - 235/65R16 >Search Tires Tire 1 - 235/60R16
Section Width: 9.25 in 235 mm
Section Width: 9.25 in 235 mm
Rim Diameter: 16 in 406.4 mm
Rim Diameter: 16 in 406.4 mm
Rim Width Range: 6.5 - 8.5 in
Rim Width Range: 6.5 - 8.5 in
Overall Diameter: 28.02 in 711.70 mm
Overall Diameter: 27.10 in 688.34 mm
Sidewall Height: 6.01 in 152.65 mm
Sidewall Height: 5.55 in 140.97 mm
Radius: 14.01 in 355.85 mm
Radius: 13.55 in 344.17 mm
Circumference: 88.02 in 2235.7 mm
Circumference: 85.13 in 2162.3 mm
Revs per Mile: 742.3
Revs per Mile: 767.5
Actual Speed: 60 mph 100 km/h
Speedometer1: 62.0 mph 103. km/h
Speedometer Difference: - Speedometer Difference: 3.394% too fast
Diameter Difference: - Diameter Difference: 3.29%