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Tire Ratings

O'Rattlecan

Redneck Prognosticator
26,687
797
Belton, MO
Alright... Someone clue me in. I have a theory of how this works, but honestly don't know.

How do you rate tire sizes? Stock tire size on my 1994 F-150 is 235/75/15. I know the last number is easy to get, but the other two?

Someone clue me in, as I'll need new tires after this season.

Ryan
 

Brian_B

blank
I am not sure what you are asking. "rate tire size"

Do you mean a conversion from metric to inches?

Try this:

http://www.dakota-truck.net/TIRECALC/tirecalc.html

I know...its a dodge site, but there are several conversions there.

BTW: you have tiny tires for a full size. Mine (stock) are 255/70/16s on the explorer (has the sport package). That translates to 30.1 tall and 10 wide.

EDIT: I think..think that the 235 is the height in millimeters and the 75 is the percentage of the height (width of tread). Someone correct me if I am wrong.
 
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Fellro

Moderator
Staff member
7,991
383
Iowa County, Iowa
on say a 235/85 r16 tire, the tire tread width is the 235 mm, the 85 is called aspect ratio, meaning thet the sidewall is 85% of the tread width, and the 16 is obviously rim size. So then a 245/75 r 16 tire is smaller diameter than the 235/85, because it is only 75% of the tread width for sidewall height.
 
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Fellro

Moderator
Staff member
7,991
383
Iowa County, Iowa

Fellro

Moderator
Staff member
7,991
383
Iowa County, Iowa
a 235/75 R15 tire has a diameter of 28.88 inches, a 255/70 r15 has a diameter of 29.06. so whatever you had for original tire size, if it was the 235's, you won't get much difference other than the width. If you had 215's, you definitely would.
http://www.csgnetwork.com/tireinfo4calc.html
 

CaFordDude

Charter Member
7,748
464
Cali
I buy all my tires from discount tire store (Americas tire store in some parts of the country) They are good price/service/knowledge wise
 

Fellro

Moderator
Staff member
7,991
383
Iowa County, Iowa
It seems counter-intuitive for the tires to be about the same, but the aspect ratio makes a big difference.
 

surewhynot

Rep whores make me sick
13,843
821
Florida
I've ran the Duelers from sears before. I think mine were 31x10.50. It was on a 95 F150 2wd. They wore like iron and had pretty good traction, on and off road. To me they were a well rounded work tire.
 

6L PWR

Kansas Chapter member
7,961
255
Osage Beach, MO
I know Z rating is the highest, no stated designation is good to 85..
Yep, according to the charts, Z is unlimited. So, ya think the tires on an SR-71 Blackbird were Z rated? 'hah'
 

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