Is that the width including the tyre bulge on the rim, my 10.5 MT's measure just over 13" at their widest point.

69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200#
best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft
best 60ft 1.36