It's been a while since I've had to shop for tires and since I'm changing rim diameters I need to see what the REAL sizes of tires in that diameter are.
No, the sidewall and rated tire size is no help because those are only suggestions. When I was shopping for 18" tires I found over a 2" variance in width and about 1" variance in diameter.
225/40 X18's ranged from 7" wide to 9.03" wide and ranged from 24.3" to 25.1" in diameter.
I used to go to Tirerack and they had a chart that gave you the real numbers, but I can't find that now.
Have they just hidden that very well or has it moved to someplace else?
In reply to carguy123:
Click on the "specs" tab on the page of the tire you are looking at. The info is there.
Thanks, that's what I was looking for.
Pretty much every manufacturer also has the specs on their website.
Another Tire Rack treat - you can see all tires for a particular wheel diameter. Useful when looking for an oddball.
Vigo
UberDork
9/8/13 8:41 p.m.
Another Tire Rack treat - you can see all tires for a particular wheel diameter. Useful when looking for an oddball.
Never noticed that one.. how do you do it?
Tires -> shop by size.
Right underneath the drop-downs for the size is "see all available tire sizes".
http://www.tirerack.com/tires/sizes/index.jsp
Actually not every manufacturer has the specs on their sites. But I've usually found that when they don't, then their specs don't match up to everyone else's such as actual tire width.
For instance the last time I checked the Goodyear site they had no widths listed but when we pulled out the tape measure they were always narrower than the competition.
And Keith, unless there's more to those calculators than meet the eye, they are using rated sizes not actual sizes. It appears they use the sidewall rating for their calcs and sidewall sizes are more of a suggestion than a hard and fast measure.
I must be doing something wrong cause when I click on the drop down that says See all sizes I just get a blank page.
I didn't post the link to the calculators, I can read your posts 
But yes, they show the rated size as opposed to actual measured sizes.
In fact, I can read well enough to find the specs on the Goodyear site in about 45 seconds. Sample: http://www.goodyear.com/en-US/tires/eagle-f1-super-car-emt?ub=Y&updatecase=passivelyStored&action=save&webprodid=57&productcode=41260950600000
You do have to click on "View tire size and specifications", though.
I have a quick formula that I use and it comes darn close.
Diameter only.
Nominal tire size in MM x aspect ratio x two, divide by 25.4 to get inches, add rim size.
That's the rated size and is correct in theory. But the actual tires do vary, thus the entire purpose of this thread.
Same tire on 2 different rims should also give a small difference in diameter as well. Mount a 225 on a 7" rim vs a 9" rim and the diameter should change a bit.
Keith Tanner wrote:
That's the rated size and is correct in theory. But the actual tires do vary, thus the entire purpose of this thread.
True .
I just put this out as a quick way to estimate.
In checking with the charts, it come out darn close.
hmm. i just checked and the 195/50R16's i just installed actually run wider (wider section and tread width) than the 205/45R16's they replaced. section width doesnt really surprise me but tread width kind of does.
