I have just changed my Pirelli Sorpions (275-55-20) for Cooper Mastercraft snows (275-65-20LT) should the different size cause any issues?

 

When your speedo says 60, you will actually be going 64...but it wont really cause any issues!
Stock Tire Search Tires Tire 1 - 275/55R20 Search Tires Tire 2 - 275/65R20 Search Tires Section Width:--Section Width:10.82 in275 mmSection Width:10.82 in275 mmRim Diameter:--Rim Diameter:20 in508 mmRim Diameter:20 in508 mmRim Width Range:Rim Width Range:7.5 - 9.5 inRim Width Range:Unrecognized tire size.Overall Diameter:--Overall Diameter:31.90 in810.26 mmOverall Diameter:34.07 in865.37 mmSidewall Height:--Sidewall Height:5.95 in151.13 mmSidewall Height:7.03 in178.56 mmRadius:--Radius:15.95 in405.13 mmRadius:17.03 in432.56 mmCircumference:--Circumference:100.2 in2545.0 mmCircumference:107.0 in2717.8 mm