Most 3 wheel electrics require 10' 6" for a right angle stacking aisle with a 48" long pallet. Then you should add 6" for ease of operation and there are other variables that may change that such as a hang on side shifter will add another 3". The right angle stacking aisle assumes that there are 4" between pallets. If you have more than that will help.
You can probably maneuver in a 10' aisle but is will be tight, not very productive and cause product damage.