My 639 has a curb weight of slightly under 2.2 tonnes.
The gross train weight exceeds 4.9 tonnes.
There is considerable tolerance required for the drivetrain to manage.
The percentage growth can be obtained from websites that display the percentage of increase in circumference. However, this is primarily attributable to the additional revolutions required to initiate movement, particularly on an incline, if so chosen.
Years ago, I upgraded the tyres on a Vito from 205/65 to 205/75 to enhance the ride quality. Over approximately 60,000 miles, it did not cause any damage. The speedometer was then as near to GPS accuracy as possible.
I would not appreciate the road noise and atmosphere, but to each their own.