Copy and paste this ; Tirerack.com Hope they answer your questions...
All the tires should be the same size. If the other tires are in place you should be able to get the size from the other tires. If not the size should be on a plate inside the drivers side door with many other specs.
of course
First off you should not install tires that are not the correct size. But if you do, make sure the tires on each axle are both the same size. Both front tires same size, and both rear tires same size.
same size as the other tires on your van,
To find the equivalent size of tires when replacing 27x1 1/4 tires, you need to consider the diameter of the wheel. The equivalent size would be 700x32c tires.
Tires come in every possible size you could imagine.
I suggest you go to www.tirerack.com You will find the correct answer there.
Tires Size - 215/60/R15" Rim Size - 15 inches
form_title= Tire Size Calculator form_header= Drive with the right size tires Want size tires do you currently have?*= _ [50] When were your tires last replaced?*= _ [50] Do you want to change tire size?*= () Yes () No
15 inch tires the exact size was 215/75R15
To determine the size of mountain bike tires you need for your bike, you should check the current tire size on your bike's tires. The size is usually printed on the sidewall of the tire. Common sizes for mountain bike tires are 26 inches, 27.5 inches, and 29 inches. Make sure to get tires that match the size of your current tires to ensure they fit properly on your bike.