The tire size is usually 185/65/14.
Look in the owners' manual or on the driver's door post.
OEM is P175/65R14
behind the drivers side rear tire on the frame
For my 94 Geo Prizm it's a 30mm.
Geo Prizm was created in 1989.
My 1991 Geo Prizm LSI does not have overdrive My 1991 Geo Prizm LSI does not have overdrive
Geo Prizm is compatible with the Toyota Corolla.
It's either 175/65/14 or 185/65/14 depending on whether or not it is a base or LSI. The 1995 Prizm LSI has 185/65/14. It might depend on the rims you have on the car too.
4 quarts
Probably 10 gallons (I own a 1996 Prizm with a 10 gallon tank).
I have a 1996 Prizm, and it has a 10 Gallon tank. Yours is most likely the same.