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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 07-22-2015, 11:51 AM   #1 (permalink)
EcoModding Lurker
 
Longsnowsm's Avatar
 
Join Date: Apr 2011
Location: US
Posts: 70

Peaty - '03 Honda Insight

Jimmy - '07 GMC Canyon 2wd, Extended Cab, SL
Thanks: 22
Thanked 12 Times in 9 Posts
Tires profiles and sizes - the pros and cons

Well I know this is an often beat dead horse here in these forums and after searching and reading I have drawn some conclusions, and yet there still(for me) are some unanswered things about the compromises that are made with tires.

When looking at tires the questions that remain for me personally are related to the trade offs of wider/taller tires(aero drag and rolling resistance) vs smaller, narrower tire for lighter weight, less rolling resistance, and aero drag. Also the factor of vehicle height as it also increases the aero drag. Has anyone come up with a magic formula for determining the rolling resistance, aero drag of the wider tires and the increase or decrease in the vehicle aero drag by raising or lowering the vehicle.

At this point I am probably going to stick with a stock size tire, but there were at least 4 sizes offered on the vehicle I am buying tires for. The default size appears to be the best compromise but is not the smallest that was offered, and far from the largest. However at some point you can clearly go too large and there is a trade off. Anyone know at one point is the break even point on tire size and profile? Thanks.

Longsnowms


Last edited by Longsnowsm; 07-22-2015 at 05:33 PM..
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 07-22-2015, 05:00 PM   #2 (permalink)
Master EcoModder
 
mcrews's Avatar
 
Join Date: Oct 2009
Location: Texas
Posts: 3,523

The Q Sold - '02 Infiniti Q45 Sport
90 day: 23.08 mpg (US)

blackie - '14 nissan altima sv
Thanks: 2,203
Thanked 663 Times in 478 Posts
your rambling encourages NOT reading......
But from the first few paragraphs I can say this:
you seem to be weighting everything equally. not so.
Taller tires barely weigh more than the stock tire.
The issue w/ 'extra wieght' is when a taller wheel/rim is added (14" to 16") then you are moving the extra weight farther out.

But the solution is much simpler than a long rambling post.
Using a scangauge, take an mpg reading at 50, 55, 60, 65, 70, for aprox 5-8 miles on a flat freeway at a cruise controlled setting.
also record the rpms.
Now you have a baseline to measure everything by.
A 5% taller tire will spIN 5% LOWER mph AT A GIVEN rpm.

Trucks are normally geared for mpg on the stock tire. so going TOO tall can be counter productive.
But by having the baseline chart, you already know where the sweet spot is on the rpm side.

And smaller diameter(than stock) tires should be edited out of your rambling. YOu are wasting reading time on a complete non-issue.
__________________
MetroMPG: "Get the MPG gauge - it turns driving into a fuel & money saving game."

ECO MODS PERFORMED:
First: ScangaugeII
http://ecomodder.com/forum/showthrea...eii-23306.html

Second: Grille Block
http://ecomodder.com/forum/showthrea...e-10912-2.html

Third: Full underbelly pan
http://ecomodder.com/forum/showthrea...q45-11402.html

Fourth: rear skirts and 30.4mpg on trip!
http://ecomodder.com/forum/showthrea...tml#post247938
  Reply With Quote
Old 07-22-2015, 05:28 PM   #3 (permalink)
EcoModding Lurker
 
Longsnowsm's Avatar
 
Join Date: Apr 2011
Location: US
Posts: 70

Peaty - '03 Honda Insight

Jimmy - '07 GMC Canyon 2wd, Extended Cab, SL
Thanks: 22
Thanked 12 Times in 9 Posts
Sorry...

Sorry for the rambling... Just been trying to sort out vehicle height, rpm, weight, and adjustments for all the above with the various tire sizes, types etc. I will clean up the original post and summarize my questions. Thanks for the feedback.
  Reply With Quote
The Following User Says Thank You to Longsnowsm For This Useful Post:
mcrews (07-22-2015)
Old 07-22-2015, 05:42 PM   #4 (permalink)
Master EcoModder
 
mcrews's Avatar
 
Join Date: Oct 2009
Location: Texas
Posts: 3,523

The Q Sold - '02 Infiniti Q45 Sport
90 day: 23.08 mpg (US)

blackie - '14 nissan altima sv
Thanks: 2,203
Thanked 663 Times in 478 Posts
I will also interject this:
most of the discussions on taller tires deal with CARS.
Trucks tend to be a little different. Mainly because most don't have the stock size anymore and that confuses the conversation.
but by doing a BASELINE at the various speeds and rpm, you can fing the sweet spot in the rpms.

Most CARS benefit from a taller tire (5-10%) than stock. There are many threads that support this.
__________________
MetroMPG: "Get the MPG gauge - it turns driving into a fuel & money saving game."

ECO MODS PERFORMED:
First: ScangaugeII
http://ecomodder.com/forum/showthrea...eii-23306.html

Second: Grille Block
http://ecomodder.com/forum/showthrea...e-10912-2.html

Third: Full underbelly pan
http://ecomodder.com/forum/showthrea...q45-11402.html

Fourth: rear skirts and 30.4mpg on trip!
http://ecomodder.com/forum/showthrea...tml#post247938
  Reply With Quote
Old 07-22-2015, 06:02 PM   #5 (permalink)
EcoModding Lurker
 
Longsnowsm's Avatar
 
Join Date: Apr 2011
Location: US
Posts: 70

Peaty - '03 Honda Insight

Jimmy - '07 GMC Canyon 2wd, Extended Cab, SL
Thanks: 22
Thanked 12 Times in 9 Posts
RPM baseline

Thanks for the feedback. I will work on developing that RPM baseline over the weekend as I will be doing a long road trip and then look to see how that affects my tire shopping from there. Thanks for the input on the increase in size recommendation as it relates to cars. I agree, the truck situation is a bit more tricky. I will check to see how that recommendation for cars might apply to a truck.

Longsnowsm
  Reply With Quote
Old 07-22-2015, 09:47 PM   #6 (permalink)
Human Environmentalist
 
redpoint5's Avatar
 
Join Date: Aug 2010
Location: Oregon
Posts: 12,811

Acura TSX - '06 Acura TSX
90 day: 24.19 mpg (US)

Lafawnda - CBR600 - '01 Honda CBR600 F4i
90 day: 47.32 mpg (US)

Big Yeller - Dodge/Cummins - '98 Dodge Ram 2500 base
90 day: 21.82 mpg (US)

Chevy ZR-2 - '03 Chevrolet S10 ZR2
90 day: 17.14 mpg (US)

Model Y - '24 Tesla Y LR AWD

Pacifica Hybrid - '21 Chrysler Pacifica Hybrid
90 day: 43.3 mpg (US)
Thanks: 4,327
Thanked 4,479 Times in 3,444 Posts
The variables are to varied. Wide vs narrow would have to factor in not only rolling resistance but wind resistance at the speeds you would normally travel. It might make sense to have wider tires for slower driving, but the increased wind resistance from the wider profile might be detrimental at higher speeds.

Probably the main factor is keeping engine RPM and BSFC in the sweet spot. For most cars, that probably means having taller "gearing" with larger diameter tires at the expense of acceleration. Ideally a change to the gearing would be made instead of changing the stock tire size.
__________________
Gas and Electric Vehicle Cost of Ownership Calculator







Give me absolute safety, or give me death!
  Reply With Quote
Old 07-23-2015, 03:24 AM   #7 (permalink)
Master EcoModder
 
Join Date: Nov 2013
Location: john o groats
Posts: 277

beastie - '89 toyota hilux dolphin motorhome

Puggie - '98 Peugeot 406 Lx
Thanks: 35
Thanked 49 Times in 41 Posts
My car i believe would benefit from one profile higher. ie going from a 55 to a 60 as i always seem to be looking for gear change around 55mph car pulls like a train at this speed in 5th. 5th gear is geared to 22mph per 1k rpm. Max torque is developed from 2k rpm up to 4k rpm. If i go for a 60 profile i think from a tyre calulation site my speedo will be 3% slower. Do 50 mph on speedo means im travelling at 51.5 mph not a huge difference but hopefully pay divdends when i come to replace tyres in a couple of months.
  Reply With Quote
Old 07-23-2015, 03:24 AM   #8 (permalink)
Master EcoModder
 
Join Date: Nov 2013
Location: john o groats
Posts: 277

beastie - '89 toyota hilux dolphin motorhome

Puggie - '98 Peugeot 406 Lx
Thanks: 35
Thanked 49 Times in 41 Posts
Ps 60 profile tyres are cheaper than 55 profile.
  Reply With Quote
Old 07-23-2015, 03:33 AM   #9 (permalink)
EcoModding Lurker
 
Join Date: Jun 2015
Location: Finland
Posts: 69
Thanks: 1
Thanked 21 Times in 15 Posts
Quote:
Originally Posted by redpoint5 View Post
It might make sense to have wider tires for slower driving
Why? (From an MPG point of view)
  Reply With Quote
Old 07-23-2015, 11:43 AM   #10 (permalink)
EcoModding Lurker
 
Katmandu's Avatar
 
Join Date: Jun 2008
Location: Murfreesboro, TN
Posts: 52
Thanks: 2
Thanked 2 Times in 2 Posts
Question

Quote:
Originally Posted by redpoint5 View Post
Probably the main factor is keeping engine RPM and BSFC in the sweet spot.
What is BSFC ?

  Reply With Quote
Reply  Post New Thread






Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com