installed 245/45zr18 rim and tires on my 2005 mustang coupe, what pressure should I inflate the tires (max tire pressure is 51). Tire shops recommended only 32-35 psi, I get a rough ride and steering is very sensitive.
Look in the manual. I don't know where you get 51, but nobody runs 51 lbs in a road Mustang, the ride would be horrible and the tires would wear out very quickly. 51 is the pressure recommended for some 3/4 ton and 1 ton Ford trucks and vans. Remember, you have a sport suspension, not a soft luxury car suspension, the steering should be sensitive. When you go to an 18 inch wheel, you have very short sidewalls to flex, the ride will always be a little harsher than with a 15 or 16 inch wheel. Much under 32 lbs, and the ride will be softer, but the handling will be less precise than designed. Most Mustangs do have a recommended pressure, front and back, of 35 lbs, some Cobras and GTs recommend 30.
The CORRECT tire pressure on all Ford products is located on the driver door jamb, where you see the label with the bar code and the VIN. There it lists the specified tire pressures for the front and rear tires. For your particular vehicle, it IS 35 psi, NOT 51! This is especially important information when setting tire pressures on 3/4 ton and heavier trucks, where the front and rear tire pressure specs. are different. Hope this helps.
When you installed the low profile tires and the larger diameter rims you made a trade off. You traded the comfortable ride of the stock tire profile, which gives you more of a sidewall to absorb the road bumps, for the current trendy look of large diameter rims and skinny sidewall tires. The steering is also sensitive because of the rigid nature of the tire/wheel combination. You really have to watch that you don't go too low with the tire pressure because those skinny sidewalls have a tendency to pull the beads loose if corners are taken too aggressively. Personally, I would start around 40psi, that's my own preference, and adjust it to your preference a few pounds either way. If you don't like the way it rides or handles, you should really go back to the stock tire size, sell the custom 18's and those rubber band tires, and get after-market rims that are the same size as the stock rims, and mount the stock size tires on them. You'll like the ride and handling better, and the after-market rims will still look cool.
