(ET) E20 Replacement Tire Size, will larger 26x12x12 tires fit?

["Markus Lorch" <mlorch vt edu>]

Hi all,

my E20 has one original 23x10.5x12 and one more 
modern turf tire of different size: 23x8.5x12.

I would like to replace the two with a matching
set just for the looks and have been told about
a slightly used set of 26x12x12 tires for a good price.

If I am right then the first 26 refers to the 
outer diameter which should still fit the wheel 
well (I think). And the last number refers to 
the rim diameter, which should also be fine.
 
The middle number I think is the width of the tire. 
Here I am not sure if the additional 1.5" will
fit the tractor. Would it add 0.75" on either side
and possibly rub against the battery box?

The E20 has 10.5 as its standard tire width, I think 
the smaller ETs had narrower tires. Does anybody 
know if a 26x12x12 would still fit and if I can 
mount such a tire on the original E20 rims. 

Thanks

Markus