Go Back   EcoModder Forum > EcoModding > General Efficiency Discussion
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 04-10-2019, 09:34 AM   #11 (permalink)
Cyborg ECU
 
California98Civic's Avatar
 
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 5,211

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 64.33 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
Thanks: 1,853
Thanked 1,552 Times in 1,056 Posts
That double claim of larger diameter (for lower RR) and narrower width (for drag reduction) has come up before in our debates, but maybe without resolution. So it is great to see confirmation from a manufacturer. The i3 tires drew all of our attention. But the claim here, by Bridgestone of increased wet weather traction is new. Anyone believe that?

__________________


See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 04-10-2019, 10:40 AM   #12 (permalink)
Master EcoModder
 
Ecky's Avatar
 
Join Date: Dec 2011
Location: Vermont
Posts: 3,498

Gaptooth (retired) - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 54.26 mpg (US)

Such Fit - '07 Honda Fit Sport
90 day: 41.27 mpg (US)

Connect - '15 Ford Transit Connect XL
90 day: 23.93 mpg (US)

K-sight - '00 Honda K-sight
90 day: 40.97 mpg (US)
Thanks: 1,286
Thanked 1,427 Times in 906 Posts
Quote:
Originally Posted by California98Civic View Post
That double claim of larger diameter (for lower RR) and narrower width (for drag reduction) has come up before in our debates, but maybe without resolution. So it is great to see confirmation from a manufacturer. The i3 tires drew all of our attention. But the claim here, by Bridgestone of increased wet weather traction is new. Anyone believe that?
I've been reading a lot about tires lately, and here's what I've picked up:

Many people put wider tires on performance cars to get a larger contact patch and more traction. This is WRONG. More contact patch does improve traction (despite what the standard friction equation from physics would have you think). However, contact patch is mostly a function of weight and air pressure, so a wider tire (all else being equal) has a contact patch with the same area that's wider but less long. This will give increased traction from lateral movement (e.g. cornering) but actually reduce traction when accelerating and braking, especially in wet conditions.
  Reply With Quote
Old 04-10-2019, 11:24 AM   #13 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,561

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,514
Thanked 3,327 Times in 2,100 Posts
Quote:
Originally Posted by Ecky View Post
I've been reading a lot about tires lately, and here's what I've picked up:

Many people put wider tires on performance cars to get a larger contact patch and more traction. This is WRONG. More contact patch does improve traction (despite what the standard friction equation from physics would have you think). However, contact patch is mostly a function of weight and air pressure, so a wider tire (all else being equal) has a contact patch with the same area that's wider but less long. This will give increased traction from lateral movement (e.g. cornering) but actually reduce traction when accelerating and braking, especially in wet conditions.
I measured contact patch at various pressures and it didn't correlate well at all.
__________________


  Reply With Quote
Old 04-10-2019, 11:36 AM   #14 (permalink)
Master EcoModder
 
Ecky's Avatar
 
Join Date: Dec 2011
Location: Vermont
Posts: 3,498

Gaptooth (retired) - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 54.26 mpg (US)

Such Fit - '07 Honda Fit Sport
90 day: 41.27 mpg (US)

Connect - '15 Ford Transit Connect XL
90 day: 23.93 mpg (US)

K-sight - '00 Honda K-sight
90 day: 40.97 mpg (US)
Thanks: 1,286
Thanked 1,427 Times in 906 Posts
Quote:
Originally Posted by Frank Lee View Post
I measured contact patch at various pressures and it didn't correlate well at all.
One article I read shows that with soft rubber compounds, you can actually roughly estimate the corner weight in a vehicle based on contact patch and pressure.

Sidewall stiffness and rubber compounds also affect the slope of the curve, of course, but the relationship is there. Or, should be at least.

Last edited by Ecky; 04-10-2019 at 11:51 AM..
  Reply With Quote
Old 04-10-2019, 12:42 PM   #15 (permalink)
Master EcoModder
 
Join Date: Feb 2014
Location: Missoula, MT
Posts: 1,745
Thanks: 118
Thanked 620 Times in 423 Posts
The contact patch size doesn't matter in that the weight per square inch goes up or down and therefore the traction available never changes. What a bigger contact patch helps with is the ability not to melt the rubber when the limits of traction are exceeded. Once the rubber starts to melt it is like driving on butter. So in the rain (or snow and ice) the narrow tire isn't melting and the smaller contact patch has an ability to poke through the standing water to the pavement.
  Reply With Quote
Old 04-11-2019, 08:28 AM   #16 (permalink)
Tire Geek
 
CapriRacer's Avatar
 
Join Date: May 2008
Location: Let's just say I'm in the US
Posts: 709
Thanks: 0
Thanked 289 Times in 181 Posts
Quote:
Originally Posted by Frank Lee View Post
I measured contact patch at various pressures and it didn't correlate well at all.
Frank, Did you publish your results?

Also, Frank is right. The idea that you can calculate the size of a tire's contact patch knowing the load and the tire pressure is incorrect. Also, a wider tire has a slightly larger footprint than a narrower tires - all other things being equal.

There used to be a webpage called "Fact or Fiction" that had data from Avon tires that proved this point, but that web page has disappeared. You can find other studies that have the data, but you have to wade through a lot of other data, because that is usually NOT the point of the study.

Update: I found an archived version here: https://web.archive.org/web/20090225...on-tires-1.htm
__________________
CapriRacer

Visit my website: www.BarrysTireTech.com
  Reply With Quote
Old 04-19-2019, 01:16 AM   #17 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 13,516
Thanks: 3,290
Thanked 4,488 Times in 3,574 Posts
Neil Blanchard provided the historical context.

Quote:
Originally Posted by California98Civic
But the claim here, by Bridgestone of increased wet weather traction is new. Anyone believe that?
https://duckduckgo.com/?q=hydroplaning

I would if I could: BMW i3 tires on MG-TC 19x3 wire wheels with knockoffs, else red Model A 19x4s from Dayton Wire Wheel. Adapted to 4x100mm.

edit:
Like this, only 19s:


__________________
.
Haiku are easy
But sometimes they don't make sense
Refrigerator

_________________

Last edited by freebeard; 04-19-2019 at 01:48 AM..
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com