Tire Size Question

[Drew Dowdell]

I've never understood how tire sizes work.

My Cadillac has 225 55 16s

I have another set of snow tires from another car.... <ahem>.... that are just laying in storage in my basement. I would like to include them with the sale of my car.

They are 205 55 16s

will they work?

[balthazar]

Tire sizing is pretty easy once you see the definition.

225 is the tread width in millileters.

55 is the sidewall height : 55% of 225 (124mm)

16 is the rim diameter they fit.

Tire height: 16" + 124mm + 124mm

With interchangability, rim diameter obviously cannot change, but both width (225) and aspect ratio (55) can quite a bit and still be safe for a given width rim. With older tire aspect ratios (ie: 60s or 70s), the sidewall is taller, which allow more flexability in fitting a given rim. For example: a 6" wide rim should be able to wear a --say-- 195wide tire up to a 235 wide one. But with shorter tires (50s, 40s, etc)- there is less sidewall flex, and I would have to imagine the range of tire widths for a given rim width is smaller. Still, I would think a 225/55 and a 205/55 could go on the same rim.

[schuby87]

Still, I would think a 225/55 and a 205/55 could go on the same rim.

X2, it should fit.

[Casket Demon]

yes they'll work just fine...smaller contact patch,but U want a skinner tire in the snow anyways (skinny tires cut through the snow where as fatter tires ride on top of the snow causing poor traction and bad handling).

[CMG]

55 is the sidewall height : 55% of 225 (124mm)

55 is actually the "aspect ratio".

The height of the sidewall compared to the section width- 55% as high as it is wide, like you say.

[balthazar]

Yes;

...both width (225) and aspect ratio (55)...

[CMG]

I know some people think the aspect ratio is the actual height of the tire- I point to radically different size tires with the same aspect ratio, some still don't see it..??

[Nick]

It depends on the width of your rim. It should fit alright fine, but you'll be stretching the tire and you'll end up with that lame euro look. Very bad for tire wear and performance, and potentially hazardous to your rims. But, they should fit, and I don't see any issues with including them in the sale.

[balthazar]

>>"I know some people think the aspect ratio is the actual height of the tire- I point to radically different size tires with the same aspect ratio, some still don't see it..?? "<<

I've encountered the opposite. Years back, many 'hot rodders' used to say "I'm putting 60s on my Nova", meaning really wide tires. Add to this that some tires in the musclecar era were marketed with their then-new aspect ratios of "60", and the misinterpretation lingered long.

[CMG]

>>"I know some people think the aspect ratio is the actual height of the tire- I point to radically different size tires with the same aspect ratio, some still don't see it..?? "<<

I've encountered the opposite. Years back, many 'hot rodders' used to say "I'm putting 60s on my Nova", meaning really wide tires. Add to this that some tires in the musclecar era were marketed with their then-new aspect ratios of "60", and the misinterpretation lingered long.

Actually now that you bring it up, I remember much of the same!!!!!!!