Here is some info from a thread a while back discussing suspension and tire sizes. I have seen and ridden in Chuck's (C9zx) car and it looks excellent.
To cut to the parts I think will help the most for your question, see the following from both Chuck (C9zx) and Scott (Qcode351Mach):
Qcode351Mach
Chuck posted up a link to eaton spring
http://www.eatonsprings.com/ where you should get your springs from. Give them a call & speak to them with your plans..If you get the correct front 1" lowering springs you will not sacrifice ride quality in fact you will enhance it... I think to get the stance your after (not having the back squat) your going to have to lower the front
The other thing I would do is consider 16" wheels all around..There's a reason new cars have 16" 17" & 18" wheel & tire combo's It will be one the best upgrades you can do to enhance handling. I've done many upgrade suspension wheel tire swaps.. Here's a great program to compare different wheel tire combos.
http://www.rimsntires.com/specs.jsp I've used this extensively on my own cars & it's never let me down. I just punched in your chosen tires on a 15" rim when you look at them rear & front the front looks like a drag race tire..Not really a great look..Also not the best setup for optimum handing.
Check out my susp upgrades to my car here I went with 18" all around.
http://www.saturdaymorninggarage.com/201...tall-3511/
C9zx
... the rear wheel size. They are ... 15x8s with 4 1/2 back spacing. ... I have 15x7 with 4 1/4 back spacing wheel vintiques on the front with 245x60x15 in the front. I feel this is the edge with 245x60x15 tires (Goodrich Radial T/As) and may be over the edge if a tire of the same size with a wider section width is used. They don't rub but, there is not much clearance. The 275s in the back are tall at 28.00 inches so it numerically lowers the effective gear ratio a bit but, it fills up the wheel wells which I like and others do not. Chuck
As Q said, you can't go wrong using parts suggested by eaton spring for a restoration or true street car. If you want to race, that is a different matter. I used a high durometer front spring eye and shackle bushings from eaton with the stock 4 leaf rear springs that are part of the "competition suspension" that came with the Q code Mustangs. I used the original front springs with 1/2 coil removed (using a cut off wheel) to get the stance I wanted. Again it is all personal preference. Chuck
Ray
