1980 duster road wheels
- Thread starter Duster80
- Start date
They're probably 6", but I can't swear to it, especially since unless you're the original owner it's hard to tell if they're the actual wheels the car had. I would probably stick around a P215 or P225/70R-14; anything wider than a 225 is going to start looking "pinched" on a skinny wheel, and anything shorter than a 70 aspect ratio won't really fill the wheelwell. Plus, as you get into the shorter aspect ratio, the tires actually "grow" in tread & bead widths. The wider tread looks good, of course, but the shorter distance from tread to the outer edge of the rim makes the "pinched" look more obvious.
If you want to play around with sizes, it's pretty simple:
P225/70R-14 translates into: P = Passenger car, 225 = section width (overall carcass width at sidewall) in millimeters, 70 = aspect ratio, meaning the sidewall's height is 70 percent of the section width, R = Radial tire, and 14 = wheel diameter.
25.4mm = 1", so a 225mm/25.4 = 8.858" wide at its widest sidewall measurement (not at the tread). 70% of 8.858" = .70 x 8.858" = 6.201" sidewall height. We multiply that times two (theres a sidewall on either side of the rim), so 6.201 x 2 = 12.402", which we then add to the size of the rim. 12.402 + 14 = 26.402" overall height. So, a P225/70R-14 is 26.4" tall and 8.9" wideoverall. A P215/70R-14 would be 25.9" tall and 8.5" wide at the sidewall. For fun, break out the calculator and see how this compares to my Imperial's rear tires, which are P255/55R-16s.
Wheel width does affect the actual overall sidewall width to some extent, since you have to pull in the beads on a skinny wheel or push them out on a wide one. This also affects your contact patch a little, as a very-narrow wheel will put a bit of a crown into it; too wide a wheel usually won't let the bead seat so it's not as big an issue in the other direction. Also keep in mind that at a 70 aspect ratio your tread width will not be anywhere near the carcass width: a P225/70R-14 BFG Radial T/A is only 6.7" wide at the tread (it varies a little by tire). It is also not recommended on wheels narrower than 6", but if you have 5.5" rims I expect you'd be fine.
If you want to play around with sizes, it's pretty simple:
P225/70R-14 translates into: P = Passenger car, 225 = section width (overall carcass width at sidewall) in millimeters, 70 = aspect ratio, meaning the sidewall's height is 70 percent of the section width, R = Radial tire, and 14 = wheel diameter.
25.4mm = 1", so a 225mm/25.4 = 8.858" wide at its widest sidewall measurement (not at the tread). 70% of 8.858" = .70 x 8.858" = 6.201" sidewall height. We multiply that times two (theres a sidewall on either side of the rim), so 6.201 x 2 = 12.402", which we then add to the size of the rim. 12.402 + 14 = 26.402" overall height. So, a P225/70R-14 is 26.4" tall and 8.9" wideoverall. A P215/70R-14 would be 25.9" tall and 8.5" wide at the sidewall. For fun, break out the calculator and see how this compares to my Imperial's rear tires, which are P255/55R-16s.
Wheel width does affect the actual overall sidewall width to some extent, since you have to pull in the beads on a skinny wheel or push them out on a wide one. This also affects your contact patch a little, as a very-narrow wheel will put a bit of a crown into it; too wide a wheel usually won't let the bead seat so it's not as big an issue in the other direction. Also keep in mind that at a 70 aspect ratio your tread width will not be anywhere near the carcass width: a P225/70R-14 BFG Radial T/A is only 6.7" wide at the tread (it varies a little by tire). It is also not recommended on wheels narrower than 6", but if you have 5.5" rims I expect you'd be fine.
Here's a quick link to some 14" BFG Radial T/As, which remain a very popular tire despite being an 40+ year-old design with a rock-hard compound. Maybe it's because they look so good. 
Click on the "Specs" tab and scroll down.
Click on the "Specs" tab and scroll down.
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