8" wheel vs 7" wheel

[pl235c]

does anybody know what the difference in overall width (section) of a 275/60/15
on a 7" wheel is compared to an 8" wheel?

 

[malibu795]

~1 roughly

 

[80 MICH BU]

http://www.maliburacing.com/forum/viewtopic.php?f=25&t=60031