What would you have done?

View attachment 180094 I ordered a set of Mclaren solid tires for my 310SL. When they arrived they looked rather small so I got out the measuring tape. The Diameter was approx 6" smaller than my original tires. I ended up taking to their tech support they reassured me that they sell this size to everyone with 12.5-80/18. Reason being that air tires squat more that solid when you apply a load.

6" is to much difference for me, and I feel like it would put to much stress on the...

What would you have done?

What would you have done?