I have done a lot of tire swapping and have a whole batch of NOS stuff. time to find out what I have and don't have. so we found a good crack cut into the driveway to measure from. drew a straight line across the tire and rolled them out. now lets pretend we had them all mounted on correct wheels with the correct amount of air in them. even though the only tire mounted was the 235 it was flat. the n78 x 15 did roll out bigger the all the rest. the 235 was the shortest. but I did not expect the 820 -15 to be bigger. then the l78 I knew was going to be just a bit shorter, as I have them on my 72. were this is not exact it will give you and ida which tire not to buy.