What is the difference in performance between 215 70 R 15 and 225 60 R 15?

Can't tell because you haven't given the whole tire number. - -

- My van tires are - - P215/65R15 95H. -That last number and letter are performance and load rating

- That P means it's a passenger vehicle tire,

- 215 is tread width in millimeters,

- 65 is the aspect ratio, it's a wide oval. ( 75 means it's rounder in cross section)

- R means it's a Radial

- 15 means it fits a 15" rim.

- 95 -is it's load range, and in the ISO/Metric Standards list '95' means each tire can support 1500 pounds weight.

- H - The final letter is it's 'speed rating' , and again in the ISO/metric system, 'H' means it's rated at speeds up to 130 mph.