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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 01-10-2020, 04:41 AM   #1 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,735

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: 1,571
Thanked 3,508 Times in 2,195 Posts
Tire efficiency

I predict a lot of what this guru says will challenge our conventional wisdom:


__________________


  Reply With Quote
The Following 3 Users Say Thank You to Frank Lee For This Useful Post:
COcyclist (02-29-2020), Fat Charlie (07-05-2020), nemo (01-10-2020)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 01-10-2020, 07:39 AM   #2 (permalink)
Master EcoModder
 
nemo's Avatar
 
Join Date: Nov 2010
Location: US
Posts: 958

Chief - '06 Pontiac Grand Prix
90 day: 23.13 mpg (US)

SF1 - '12 Ford Fiesta S
90 day: 21.28 mpg (US)
Thanks: 184
Thanked 218 Times in 172 Posts
Some of these points have been discussed. Tire pressure in relation to the failure caused by different surfaces say rocks and pot holes, for example. The big take away here is optimization. Each "car" location of use and actual usage ( laden be unladen) will determine best pressure. Can you imagine you stop to pick some one up and need to increase you tire pressure by two PSI.

One area of interest was negative space and tire pressure but for most of us we drive various surfaces. This is more relevant to racing than everyday.
__________________

  Reply With Quote
Old 01-10-2020, 08:49 AM   #3 (permalink)
Tire Geek
 
CapriRacer's Avatar
 
Join Date: May 2008
Location: Let's just say I'm in the US
Posts: 743
Thanks: 1
Thanked 335 Times in 207 Posts
I've only got 5 minutes in, and already, there is a lot wrong by that "expert". Please be aware that they are discussing bicycle tires and those are different than tires that are designed for 4 wheeled vehicles.

But one thing he did get right that needs to be emphasized - what is written on the sidewall has nothing to do with what you ought to run.

I'll give a more complete report later - when I have a bit more time .
__________________
CapriRacer

Visit my website: www.BarrysTireTech.com
  Reply With Quote
The Following 6 Users Say Thank You to CapriRacer For This Useful Post:
aerohead (08-07-2020), COcyclist (02-27-2020), Daox (01-11-2020), Fat Charlie (07-05-2020), MeteorGray (01-10-2020), Xist (01-13-2020)
Old 01-11-2020, 11:11 AM   #4 (permalink)
Tire Geek
 
CapriRacer's Avatar
 
Join Date: May 2008
Location: Let's just say I'm in the US
Posts: 743
Thanks: 1
Thanked 335 Times in 207 Posts
I’ve now watched the video. Here are my comments:

First, the video is discussing tires used on racing bicycles. Not only is racing of any sort a peculiar activity, racing bicycles is even more peculiar and has only a small cross application to street cars.

Burst pressure: The guy got it backwards. The standard comes first, then the tire is designed to that standard. ETRTO (European Tire and Rim Technical Organization) is one of several tire standardizing organizations in the world. The US counterpart is TRA (The Tire and Rim Association). TRA does NOT publish bicycle tire standards because no one manufactures bicycle tires in the US.

While it maybe true that the burst pressure of bicycle tires is about twice the max pressure listed, that is NOT true for car tires. The value is 3 times or more the max pressure. – and, No!, the burst pressure has nothing to do with the max pressure. The burst pressure is dependent on the fatigue strength of the car tire at the rated inflation – and for Standard Load Passenger Car tires, that is 35 psi – and those tires will be labeled with a max pressure of either 35, 44, or 51 psi.

Further, tires are NOT labeled with a recommended pressure. They are labeled with either a MAX pressure or a rated pressure (as in Max load XXXX at YY pressure). That is true for ALL tires, regardless of what their intended use is – meaning that even tires for farm tractors will be labeled with either the max or rated pressure, never a recommended pressure.

Footprint: Because bicycles lean in turns, the tread surface is rounded. That produces a footprint that is narrow and long – and that is true even when the bike is cornering.

By contrast, a car tire doesn’t lean into the corner. It tends to lean more away from the corner, so it is common for cars to start off with negative camber (leans in at the top), which results in a vertical stance (sort of!) when cornering. Also, most cars are designed NOT to be cornered severely, and have to be adjusted if the car is adapted for racing.

The fact that the bicycle tire footprint is small and narrow is more affected by the macrotexture of the pavement than car tires. (They used the term “negative space” where I am using the term “macrotexture”). That means that racing bikes can benefit from changes in inflation pressure due to road texture – much more than street cars. The idea that a racing bike should use less inflation pressure on more coarse pavement has merit, but that does not apply to car tires – unless one is racing a car. Further, the racing bike tire needs much less fatigue resistance than a street car tire – and higher inflation pressures help fatigue resistance.

Latex vs Butyl Rubber: Butyl rubbers are used where air retention is needed. In a car tire, that’s the innerliner – the innermost layer of rubber. In a bicycle tire, using an innerliner adds weight, so some bicycle tires are made of butyl throughout to reduce the weight – BUT – a racing tire (both bicycle and car racing tires) don’t need to hold air pressure for very long – just enough to finish the race – so they may not even use butyl at all.

And there you have it!

Again, be aware that these guys are discussing tires on racing bicycles. That's quite different than car tires used on the street.
__________________
CapriRacer

Visit my website: www.BarrysTireTech.com
  Reply With Quote
The Following 8 Users Say Thank You to CapriRacer For This Useful Post:
aerohead (04-01-2020), COcyclist (02-27-2020), Fat Charlie (07-05-2020), Frank Lee (01-11-2020), Hersbird (01-13-2020), MeteorGray (01-15-2020), Vman455 (01-11-2020), Xist (01-13-2020)
Old 01-11-2020, 10:31 PM   #5 (permalink)
Tyrant-at-large
 
Vman455's Avatar
 
Join Date: Feb 2012
Location: Champaign, IL
Posts: 1,653

Little Red - retired - '05 Honda Civic EX
90 day: 49.03 mpg (US)

Pope Pious the Prius - '13 Toyota Prius Two
Team Toyota
SUV
90 day: 59.13 mpg (US)
Thanks: 176
Thanked 1,444 Times in 763 Posts
Quote:
Originally Posted by CapriRacer View Post
Latex vs Butyl Rubber: Butyl rubbers are used where air retention is needed. In a car tire, that’s the innerliner – the innermost layer of rubber. In a bicycle tire, using an innerliner adds weight, so some bicycle tires are made of butyl throughout to reduce the weight – BUT – a racing tire (both bicycle and car racing tires) don’t need to hold air pressure for very long – just enough to finish the race – so they may not even use butyl at all.
Former bike racer here. Yep, a lot of people have switched to latex tubes for racing (and some for training); tubeless road bicycle wheels and tires have been a thing for 10+ years, but have been slow to catch on.
__________________

  Reply With Quote
The Following 2 Users Say Thank You to Vman455 For This Useful Post:
aerohead (04-01-2020), CapriRacer (01-12-2020)
Old 01-12-2020, 08:31 AM   #6 (permalink)
Tire Geek
 
CapriRacer's Avatar
 
Join Date: May 2008
Location: Let's just say I'm in the US
Posts: 743
Thanks: 1
Thanked 335 Times in 207 Posts
Quote:
Originally Posted by Vman455 View Post
Former bike racer here. Yep, a lot of people have switched to latex tubes for racing (and some for training); tubeless road bicycle wheels and tires have been a thing for 10+ years, but have been slow to catch on.
Thanks for that. I keep forgetting that bicycle tires frequently use tubes.
__________________
CapriRacer

Visit my website: www.BarrysTireTech.com
  Reply With Quote
Old 01-12-2020, 03:16 PM   #7 (permalink)
Tyrant-at-large
 
Vman455's Avatar
 
Join Date: Feb 2012
Location: Champaign, IL
Posts: 1,653

Little Red - retired - '05 Honda Civic EX
90 day: 49.03 mpg (US)

Pope Pious the Prius - '13 Toyota Prius Two
Team Toyota
SUV
90 day: 59.13 mpg (US)
Thanks: 176
Thanked 1,444 Times in 763 Posts
Quote:
Originally Posted by CapriRacer View Post
Thanks for that. I keep forgetting that bicycle tires frequently use tubes.
You might know the answer to this: Prevailing wisdom at Slowtwitch is that latex tubes are less resistant to puncture than butyl. Is that actually true?
__________________

  Reply With Quote
The Following User Says Thank You to Vman455 For This Useful Post:
aerohead (04-01-2020)
Old 01-13-2020, 08:12 AM   #8 (permalink)
Tire Geek
 
CapriRacer's Avatar
 
Join Date: May 2008
Location: Let's just say I'm in the US
Posts: 743
Thanks: 1
Thanked 335 Times in 207 Posts
Quote:
Originally Posted by Vman455 View Post
You might know the answer to this: Prevailing wisdom at Slowtwitch is that latex tubes are less resistant to puncture than butyl. Is that actually true?
I'm not a rubber chemist, so I don't know. I tried looking this up on the internet and didn't come up with an answer.

But I would think this has more to do with the formulation of the compound itself, rather than what type of rubber is being used. That might explain why I didn't find an answer.
__________________
CapriRacer

Visit my website: www.BarrysTireTech.com
  Reply With Quote
The Following User Says Thank You to CapriRacer For This Useful Post:
aerohead (08-07-2020)
Old 02-29-2020, 02:36 PM   #9 (permalink)
Aero Wannabe
 
COcyclist's Avatar
 
Join Date: Dec 2007
Location: NW Colo
Posts: 640

TDi - '04 VW Golf
TEAM VW AUDI Group
90 day: 53.89 mpg (US)
Thanks: 498
Thanked 160 Times in 126 Posts
Great link! Thanks Frank. Yes, the trend toward bigger tires and lower pressure on road bicycles is a thing (except in a perfectly smooth velodrome). I have read several recent scientific studies conducted with bicycle tires on a rolling rough surface showing that lower pressures have measurably lower rolling resistance than the max pressure we used to run back in the day. “Gravel” riding and racing is adding to common acceptance of using wider/lower pressure tires.

However, this is primarily a motorized modding site and we should be cautious of using test data developed for road bicycles and applying generalizations to cars. For one thing, cars have sophisticated suspensions. The inflated tire IS the first and most important suspension on a road bicycle. Bike tires are round in cross section, car tires are square where they meet the road and have several steel belts to keep that profile flat in cross section. In my experience I have found higher pressure car tires roll easier and return higher fuel mileage.
__________________
60 mpg hwy highest, 50+mpg lifetime
TDi=fast frugal fun
https://ecomodder.com/forum/showthre...tml#post621801


Quote:
Originally Posted by freebeard View Post
The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.

Last edited by COcyclist; 03-01-2020 at 11:08 AM..
  Reply With Quote
The Following User Says Thank You to COcyclist For This Useful Post:
Fat Charlie (07-05-2020)
Old 03-26-2020, 03:05 PM   #10 (permalink)
Master EcoModder
 
Ecky's Avatar
 
Join Date: Dec 2011
Location: Vermont
Posts: 3,991

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: 24.03 mpg (US)

K-sight - '00 Honda K-sight
Team Honda
90 day: 46.38 mpg (US)
Thanks: 1,756
Thanked 1,693 Times in 1,082 Posts
I would add that in the video, they are not discussing rolling resistance, but instead, how "fast" the bicycle tire is. A bicycle for racing typically does not have suspension, and can be "faster" by reducing cyclist fatigue, or by allowing higher speed cornering, or many other factors even if that comes at the expense of a tiny amount of absolute rolling resistance. Maybe I'm confusing the their terminology but from how he was describing his testing procedure it seemed he was looking at lap times, or sprint times.

Although it wasn't stated explicitly, I gather that as some point, rolling resistance improvements diminish sufficiently as to not be "worth" the additional harshness and vibration.

  Reply With Quote
The Following 2 Users Say Thank You to Ecky For This Useful Post:
COcyclist (09-28-2020), Fat Charlie (07-05-2020)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com