If you look at the picture of the “Pink MG” in the gallery, you’ll see the new 14″ x 6″ rims (by US Wheel) and the P185/70R-14 Sumitomo tires on the car.
Due to the lighter weight, you don’t need a lot of air pressure. I started with 20 lbs all around and adusted the air pressure to detect the changes. You’ll find a pressure you can live with that keeps the tire wearing properly and doesn’t give a brick like ride.
When Bill Collins VW based “Angelica” was my first “Pink MG”, I ended up with 14 lbs in the fronts and 18 lbs in the rears to get the desired handling. This was after removing front leaves and reducing the diamter of the rear torsion bars too. The car had stock VW sized P165/80R-15 tires.
I have access to a tire machine and Snap-On dynamic balancer at the local Navy Base’s Auto Craft Shop. I buy tires from http://www.tirerack.com and mount and balance them myself. I have also bought from http://www.discounttiredirect.com with equally good results.
Whatever you buy, be sure they clear and are not too wide for your rims. I think the OEM Chevette rims are 5.5″ wide and 13″ in diameter. You may want to invest in a 14″ rim, like I did. If not, a P16580R-13 or P175R75x13 might be a good choice.