A Cars forum. AutoBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AutoBanter forum » Auto newsgroups » Technology
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Strangest Tire Question EVERRR...



 
 
Thread Tools Display Modes
  #1  
Old April 29th 20, 09:35 PM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 539
Default Strangest Tire Question EVERRR...

Strangest Tire Question EVERRR...

Has anyone ever calculated or estimated the area, in square inches/square cm, of the *surface of the inside* of a tire?

Does at least an average exist out there, for broad categories: passenger car, SUV-light truck, and commercial truck?

Just curious, Thanks!
Ads
  #3  
Old May 1st 20, 03:25 PM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 539
Default Strangest Tire Question EVERRR...

Steve W.:

I went to several tire mfg. sites, but could not find such information. I guess it's
time for some E-mails & phone calls.
  #4  
Old May 1st 20, 11:24 PM posted to rec.autos.tech
Arlen Holder[_3_]
external usenet poster
 
Posts: 5
Default Strangest Tire Question EVERRR...

In response to what > wrote :

> I went to several tire mfg. sites, but could not find such information. I guess it's
> time for some E-mails & phone calls.


What tools do we have to solve the problem?
o Let's start with shape & terminology:
<https://tireguides.com/TireTips/TireDocument/9>

That gives us these perhaps relevant terms:
o Tread width
o Section height
o Aspect ratio
o Rolling circumference
etc.
Where for now I'll ignore there's a difference between
o free (i.e., unloaded), and,
o loaded

Then, using this tire-size calculator:
<https://tiresize.com/calculator/>
And ignoring sig fig approximations (so I can just cut & paste numbers)...

Assume a P200/50R15 for easy numbers & using only the 1st URL above:
o Diameter = 582mm (22.9")
o Width = 200mm (7.9")
o Sidewall = 99mm (3.9")
o Circum. = 1,824mm (71.8")
o Revs/Mile = 882
Also noting:
o Rim diameter = 381mm (15")

Assuming the carcass inside & outside surface is "similar" in both shape &
surface area, we easily arrive at a gross _approximation_ of:
o Tread area = ~200mm wide times ~1,824mm around = ~364,800‬sq mm
o Sidewall area = ~99mm times ~1,824mm around times 2 = ~361,152sq mm
Which calculates to...
o Total U shaped carcass = ~364,800‬sq mm + ~361,152sq mm
Which comes to roughly ~725,952‬sq mm

Given the sidewall area is probably more accurately done with donuts:
<https://www.spikevm.com/calculators/area-perimeter/area-donut.php>

Where the terms appear to be:
o Diameter of the Whole Area = 582mm
o Diameter of Inside Area = 381mm
Which calculates out to:
o Area = 152,023.9sq mm
o Outer Perimeter = 1,828.4mm
o Inner Perimeter = 1,196.9mm
o Total Perimeter = 1,196.9mm

Using these numbers for sidewall area in the previous calculation:
o Tread area = ~200mm wide times ~1,824mm around = ~364,800‬sq mm
o Sidewall area = ~152,023.9sq mm times 2 = ~304,047.8‬sq mm
o Total U shaped carcass = ~364,800‬sq mm + ~304,047.8‬sq mm
Which comes to roughly ~668,847.8‬sq mm

In summary, and knowing the inside dimensions must be smaller than the
outside dimensions, I'd guess it's around 600,000sq mm to 700,000sq mm.

But that's only a gross approximation.
o How much accuracy does the OP need?
--
Adults gather on Usenet to politely learn via public technical discussion.


  #5  
Old May 2nd 20, 12:41 AM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 539
Default Strangest Tire Question EVERRR...

Arlen Holder - wow! You went to town on the math!

How precise? Ohh, just an average. It's something I'm working on, so an average
sized automobile tire is all I'm asking about. 215/6R16ish.

Thanks for the hard work though.
  #6  
Old May 2nd 20, 01:06 AM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 539
Default Strangest Tire Question EVERRR...

Arlen Holder:

So 725,000 sq mm approximates 1,224 sq in. internal area of your example tire.

If a particular vehicle requires 32psi cold air pressure in that tire, that equates to 32 * 1,224sq. in = 39,168 total
pounds of air pressure against the interior wall of that tire! Wow!

If we increase that 32psi figure by 10%, that's 35.2psi.

35.2 x 1,224 = 39,564 total pounds of pressure against the wall of that same
tire. An increase of only 1.01% in the total pressure against it.

So much for my theory that each additional pound of air pressure exponentiates the total pressure imposed on
the inside of that tire.
  #8  
Old May 2nd 20, 09:33 PM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 539
Default Strangest Tire Question EVERRR...

AMuzi:

Well, to me, 'per square inch' means exactly that. 35lbs per every square inch of
the tire cavity and outer edge of accompanying rim or wheel surface.
  #9  
Old May 2nd 20, 10:45 PM posted to rec.autos.tech,alt.home.repair
Arlen Holder[_4_]
external usenet poster
 
Posts: 11
Default Strangest Tire Question EVERRR...

In response to what > wrote :

> It's something I'm working on, so an average
> sized automobile tire is all I'm asking about. 215/6R16ish.


I just noticed something interesting when it comes to 'averages'.
o All you need is the tread width & the aspect ratio & rim size.

That is...
o For a 40 series tire, it's 2x40, i.e., tread area times 180%
o For a 50 series tire, it's 2x50, i.e., tread area times 200%
o For a 60 series tire, it's 2x60, i.e., tread area times 220%
etc.

Notice an aspect ratio of, oh, say, 50 is 50% of the tread width.
o So the surface area is a function of the tread width & aspect ratio.

If the tire is a 50-series tire, the sidewall area is approximately 100%
more than the tread area (i.e., 50% times 2 sidewalls).

For a 60 series tire, the sidewall area is approximately 120% more than the
tread area (i.e., 60% times 2 sidewalls).

In short, for a quick mental calculation all you need is the tread area and
the sidewall-to-tread ratio, where the tread area is simply the width times
the circumference of the tire.

So, for your P215/60R16, this calculator tells me:
<https://tiresize.com/calculator/>
o Diameter = 26.2"
o Width = 8.5"
o Sidewall = 5.1"
o Circumference = 82.1"
o Revs/Mile = 771

The area of the tread would be its width time the circumference:
o Tread area = 8.5" times 26.2" = 222.7 sq inches

Since it's a 60-series tire, the sidewall area is 120% of that.
o Sidewall area = 222.7sq inches time 120% = 267.24 sq inches

In summary, you just take the tread area and multiply it by the percent:
o For a 40 series tire, surface area is tread area times 180%
o For a 50 series tire, surface area is tread area times 200%
o For a 60 series tire, surface area is tread area times 220%
etc.
--
Each thread on Usenet should add unique value to our combined knowledge.
  #10  
Old May 3rd 20, 01:50 AM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 539
Default Strangest Tire Question EVERRR...

Arlen Holder:

So rounded off we'll just say 270 sq. inch of area inside the avg. passenger
tire. I think something was wrong with that online calculator I was using last
night to convert square mm to square inches. For a similar tire I was getting,
if I recall,1,220-something square inches? I suspected something was off!

So the air inside the tire inflated to 35psi is pressing down on each one of
those 270 square inches with 35 lbs of force. So a more sane 9,450lbs of
total pressure on the inside wall of that tire. Probably closer to 7,000ish if
you consider that side of the rim which completes the inside of that total air
cavity at each corner of our daily vehicles.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tire Plus-Sizing Question: Why MUST Tire/Wheel Get WIDER When +Sizing? [email protected] Technology 43 May 6th 12 08:18 PM
Strangest repairs? Steve W.[_4_] Technology 21 June 19th 08 04:39 PM
clutch question, manual tire changer question Troy Jeep 13 August 26th 05 04:59 AM
v6 accord tire question, can I put 225R15 tire to my OEM wheel of 205/R15? [email protected] Honda 0 February 3rd 05 11:37 PM
Attn Tire experts. Tire valve stem question Jim Smith Saturn 1 June 17th 04 07:03 AM


All times are GMT +1. The time now is 07:43 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AutoBanter.
The comments are property of their posters.