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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 02-22-2013, 09:12 AM   #1 (permalink)
EcoModding Lurker
 
Join Date: Nov 2011
Location: Central NY State
Posts: 14
Thanks: 1
Thanked 0 Times in 0 Posts
Question Weight vs Diameter of Tire??

Hey all,

I was looking to get some tires for my 86 yota pickup 4wd. It has a 4cyl. 5 speed tranny. Of course i am looking to get the best mpg.

A 235/75/15 is about 29" diameter and weights 35-37 lbs.

A 225/75/15 is about 28" diameter and weights 27-28 lbs. (stock size)

My question what would give the best mpg? The larger tire making the gears a little taller but heavier? OR The smaller and lighter tire with stock gearing.

I currently have some old mismatched 235's on some steels, but the new tires will go on some OEM alloys. I am currently getting about 23 - 24 maybe?? At best.

Thanks,
Kirk

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 02-22-2013, 10:03 AM   #2 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

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: 1,585
Thanked 3,555 Times in 2,218 Posts
I think in the case of a m/t pickup, stock size is best.
__________________


  Reply With Quote
Old 02-22-2013, 11:24 AM   #3 (permalink)
Master EcoModder
 
Join Date: Oct 2011
Location: ellington, ct
Posts: 829
Thanks: 44
Thanked 104 Times in 80 Posts
You have the 5 speed OD tranny which I think gives you a pretty good OD ratio in stock form. I don't think the slight change in final drive will over come the weight penalty, especially since it is rotational weight.

Also, the stock tires are likely to be a fair bit cheaper.
  Reply With Quote
Old 02-22-2013, 01:41 PM   #4 (permalink)
.........................
 
darcane's Avatar
 
Join Date: Aug 2009
Location: Buckley, WA
Posts: 1,597
Thanks: 391
Thanked 488 Times in 316 Posts
That's a large weight gain for a small increase in tire size. Are the smaller tires P (passenger tires) and the larger LT (Light Truck)? Or are both the same type?

I went from a P to an LT on my Silverado. Even though the size was the same and I could run higher tire pressures, the weight went up and fuel economy went down (even after they were broke in). Between those two options, the smaller is likely the better of the two.

http://ecomodder.com/forum/showthrea...hts-19698.html
__________________
Past Cars:

2001 Civic HX Mods

CTS-V

2003 Silverado Mods
  Reply With Quote
Old 02-22-2013, 10:04 PM   #5 (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
Why guess?

What is the rpm at 50, 60, 65, 70? (for what you currently have)
then do the % change with the size not on the truck.
__________________
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 02-22-2013, 10:11 PM   #6 (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
not sure were you got your weight but it's way off.
the tires (just tires) are 2lbs apart.
weight issue is a mote point.
Kumho Solus KR21
the tire revolutions are 734 and 716. that barely 3%. Statisticly you need 5% + to really be able to notice any difference.
__________________
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 02-22-2013, 11:33 PM   #7 (permalink)
EcoModding Lurker
 
Join Date: Nov 2011
Location: Central NY State
Posts: 14
Thanks: 1
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by darcane View Post
That's a large weight gain for a small increase in tire size. Are the smaller tires P (passenger tires) and the larger LT (Light Truck)? Or are both the same type?

I went from a P to an LT on my Silverado. Even though the size was the same and I could run higher tire pressures, the weight went up and fuel economy went down (even after they were broke in). Between those two options, the smaller is likely the better of the two.
yes it is a large weight gain, although i just checked the specs and it depends on which tire brand we are looking at. The specs vary a significant amount. The above LT tire was actually 40 lbs. and the P tire was 27 lbs. The tires i was looking at were the Eldorado ZTR as they are available locally.

The Toyo Open Countrys P225 weigh 27.8 lbs. and the LT235 weigh 34.4 lbs. A much smaller difference. Though the P235 still weighs 34.2 lbs.!

Thanks for sharing your experience on the weight gain.

Quote:
Originally Posted by mcrews View Post
Why guess?

What is the rpm at 50, 60, 65, 70? (for what you currently have)
then do the % change with the size not on the truck.
I know at 55 mph i'm running at 2200 rpm in 5th gear. That is with the oddball 235's...
  Reply With Quote
Old 02-22-2013, 11:55 PM   #8 (permalink)
EcoModding Lurker
 
Join Date: Nov 2011
Location: Central NY State
Posts: 14
Thanks: 1
Thanked 0 Times in 0 Posts
True for the kumho solus...

Quote:
Originally Posted by mcrews View Post
not sure were you got your weight but it's way off.
the tires (just tires) are 2lbs apart.
weight issue is a mote point.

the tire revolutions are 734 and 716. that barely 3%. Statisticly you need 5% + to really be able to notice any difference.
I was comparing a "P" tire to a "LT" tire. The tire brands i was looking at had only one preferred size in each of the two classes - P, LT. I guess i was comparing apples to oranges in a way? So depending on brand i may be able to get the weight down.

Im looking for an All Terrain tire BTW. it kinda limits the options a bit.

Thanks for the info on statistics. I bet i might be able to "just" tell a difference 'cause my truck lugs a bit now with the 235's.
  Reply With Quote
Old 02-23-2013, 12:01 AM   #9 (permalink)
EcoModding Lurker
 
Join Date: Nov 2011
Location: Central NY State
Posts: 14
Thanks: 1
Thanked 0 Times in 0 Posts
Thank you all for your support and guidance!

I will look at the "P" tires for the weight advantage (price too) and probably go with the slightly narrower and smaller stock tire despite the small difference. Though some brands/models the difference is greater.
  Reply With Quote
Old 02-23-2013, 07:57 AM   #10 (permalink)
Tire Geek
 
CapriRacer's Avatar
 
Join Date: May 2008
Location: Let's just say I'm in the US
Posts: 794
Thanks: 4
Thanked 388 Times in 237 Posts
Just to put this all in perspective:

The larger tire will result in ever so slight improvements in fuel economy - all other things being equal. The biggest problem is the "all other things" part.

Changing from P type tires to LT type tires is the wrong direction for F/E. LT tires are "work" tires and F/E isn't much of a consideration.

All Terrain tires will be worse than All Season tires. More mass.

There are tires with improved RR, but they frequently have sacrifices in treadwear or traction. That might be OK with you, but for many, it's not.

__________________
CapriRacer

Visit my website: www.BarrysTireTech.com
New Content every month!
  Reply With Quote
Reply  Post New Thread


Thread Tools




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