Another One!!

[Volfy]

What @Snicklefritz is getting at is: "wheel size" in typical North American parlance means 18", 19", etc., whereas "tire size" means 255/30/R19, 275/30/19, etc.

About the only times I see cars rolling on "wheels", are in those police pursuit videos where the car running from police had their tire(s) shredded by spike strips.

That said... I think we all knew what @7Andrei7 was talking about. I'm sure his English is wayyy better than my German/Romanian.

 

[7Andrei7]

What @Snicklefritz is getting at is: "wheel size" in typical North American parlance means 18", 19", etc., whereas "tire size" means 255/30/R19, 275/30/19, etc.

What do you call the wheel+tire of a car? Is there no word for it?
I thought you can use "wheel" for both wheel and wheel+tire and people understand based on context.

 

[JSolo]

I always understood tire sizes to be inclusive of the wheel diameter. To add to confusion, you can have two identically sized tires (ie 245/40/18), but having different diameters and thus circumference/revs per mile. This last part really bugs me. When comparing tires, I now look at revs/mile as another factor.

ps. I doubt we'll see the metric system fully implemented here in my lifetime....... because.. who goes to the grocery store to buy a kilo of sugar or flour?

 

[7Andrei7]

To add to confusion, you can have two identically sized tires (ie 245/40/18),

How? Is it just based on thread depth?

 

[JSolo]

How? Is it just based on thread depth?

I think it's based on how the mfg actually measures the tire size - tread depth, sidewall height. Overall diameter and revs/mil are about as absolute as it gets.

 

[rcorona]

I think you might not know how tire sizes work.

Both OEM 225/40R19 and 255/35R19 wheels (wheel+tire) have a diameter of 26"

His setup is:
255/30/R19 = 25"
and
275/30/19 = 25.5"

That's a significant difference.
You can compare here: Tire Size Calculator

Hey everyone, I made a mistake. I originally said my tires had a 30 aspect ration but edited the post because they are actually 255/35/R19 and 275/35/R19

 

[rcorona]

I'm experiencing the same right now. Thinking of going back to a square setup. My current setup is 255/35/R19 in the front and 275/35/R19 in the rear. Hoping that a narrower rear tire may help with the wear but not completely sure.

Another thought I had, has anyone tried aligning the rear without as much toe from the Kia Specs? Kia factory specs have the rear toe'd in a bit. Wondering if aligning them straighter without as much toe would help with the lowered cars eating through tires? I've also noticed some squirrely behavior while driving in the wet.

Kinda wanted to steer the convo towards the 2nd part of my post, “Another thought I had, has anyone tried aligning the rear without as much toe from the Kia Specs? Kia factory specs have the rear toe'd in a bit. Wondering if aligning them straighter without as much toe would help with the lowered cars eating through tires? I've also noticed some squirrely behavior while driving in the wet.”

 

[bfglitch]

Hey everyone, I made a mistake. I originally said my tires had a 30 aspect ration but edited the post because they are actually 255/35/R19 and 275/35/R19

That's still quite a difference. 26" tire diameter on one wheel and 26.6" on the other. 774.9 revs per mile on one, and 758.8 revs per mile on the other. Most manufacturers recommend the difference in size between the front and the back to be even less than that, and that's before any tire wear. Definitely not as bad as what you originally had referenced. Also it still technically depends on the manufacturer of the tire as well.

 

[rcorona]

That's still quite a difference. 26" tire diameter on one wheel and 26.6" on the other. 774.9 revs per mile on one, and 758.8 revs per mile on the other. Most manufacturers recommend the difference in size between the front and the back to be even less than that, and that's before any tire wear. Definitely not as bad as what you originally had referenced. Also it still technically depends on the manufacturer of the tire as well.

Yeah I'm looking into going to a square setup. I'd want to get rid of my 9.5" width rear wheels and just get 2 more of the 8.5" width front wheels I have, and then get 4 of the same size tires.

 

[Thomby]

How? Is it just based on thread depth?

I think it's based on how the mfg actually measures the tire size - tread depth, sidewall height. Overall diameter and revs/mil are about as absolute as it gets.

I thought it was more that when you put the same tire on different wheel widths, you change the tread/sidewall boundary a small amount which in turn impacts the diameter (ie height is only absolute for a given wheel width). Or is that only the case for extremely stretched tires?

 

[Volfy]

What do you call the wheel+tire of a car? Is there no word for it?
I thought you can use "wheel" for both wheel and wheel+tire and people understand based on context.

In the discussion leading up to this sidebar debate, the topic was squarely on varying TIRE SIZES of the same wheel diameter (19"). So... if it were me writing a post, that is the term I would use, in order to be more concise and to-the-point. Not to say a different choice of words wouldn't be understood. Clearly you post did manage to convey your intent, even if it raised a comment or two.

You're correct that in general parlance, "wheels" can be used to refer to more than just the "rims". Not unheard of for somebody to say: "Hey man, I just got me a new set of wheels!" While it is arguably common usage, it is fraught with ambiguities. "A new set of wheels" can mean a set of rims, or a set of rims + tires, or a whole car!

In such cases, you're correct that context is often the tie-breaker used by the listener to decipher what exactly was meant.

 

[Volfy]

...you can have two identically sized tires (ie 245/40/18), but having different diameters and thus circumference/revs per mile. This last part really bugs me. When comparing tires, I now look at revs/mile as another factor.

IMO, the proper term for that should be ROLLING DIAMETER, which can be directly compared to the diameter based on the tire size designation, like 245/40R18. I never did like mfrs/retailers using the term "revs/mile", which is just a derivative of rolling diameter:

Revs/mile = 1 mile / (rolling diameter x pi)

But I understand why they do that... because that is precisely what mfrs measure directly in order to calculate the effective rolling diameter.