Dually truck tire replacement

You have to be careful to maintain the distance between tires. Too clode and they could rub under load causing a failure. So yes aspect ratio is important on a dually

Suggest using "rev's per mile" over just dia...have found there is difference between exact same dia's, but different OEMs and even within the same OEM, but different models

Aspect ratio? As in the "75" in that tire size?

That is pretty important. It IS the tire height.

245=tread width in mm
75=sidewall height as a % of tread width. ex: 245 x 0.75=183.75mm
17=rim diameter in inches

So...

total sidewall height in mm = 183.75*2=367.5
total sidewall height in inches = 367.5/25.4=14.47 inches
total diameter = 14.47+17 = 31.47 inches

Of course, there are discrepancies from tire to tire and manufacturer to manufacturer. But that is what the numbers are suppose to mean.

parker.rowe wrote:
Aspect ratio? As in the "75" in that tire size?

That is pretty important. It IS the tire height.

245=tread width in mm
75=sidewall height as a % of tread width. ex: 245 x 0.75=183.75mm
17=rim diameter in inches

So...

total sidewall height in mm = 183.75*2=367.5
total sidewall height in inches = 367.5/25.4=14.47 inches
total diameter = 14.47+17 = 31.47 inches

Of course, there are discrepancies from tire to tire and manufacturer to manufacturer. But that is what the numbers are suppose to mean.

I see - if replacing just one of the tires in a dually that this would be critical

But if you replace all 4 is aspect ratio critical?

paulbeauchemin wrote:

parker.rowe wrote:
Aspect ratio? As in the "75" in that tire size?

That is pretty important. It IS the tire height.

245=tread width in mm
75=sidewall height as a % of tread width. ex: 245 x 0.75=183.75mm
17=rim diameter in inches

So...

total sidewall height in mm = 183.75*2=367.5
total sidewall height in inches = 367.5/25.4=14.47 inches
total diameter = 14.47+17 = 31.47 inches

Of course, there are discrepancies from tire to tire and manufacturer to manufacturer. But that is what the numbers are suppose to mean.

I see - if replacing just one of the tires in a dually that this would be critical

But if you replace all 4 is aspect ratio critical?

No, it's not. Neither is diameter within reason. Small change in dia will be indiscernable. Even a couple inches in dia will not make much difference.
I'd run 255-80-17s. A little extra meat on the rims would be nice compared to 245s.

paulbeauchemin wrote:


I see - if replacing just one of the tires in a dually that this would be critical

But if you replace all 4 is aspect ratio critical?

As long as it isn't 4wd, no. Front and rear tires need to be the same diameter in 4wd, or the transfer case won't be happy.