Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now

Now available from EcoModder: ScanGauge II fuel economy gauge.  Click for details.  

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 05-23-2011, 01:38 AM   #1 (permalink)
60+ mpg at posted speeds
 
California98Civic's Avatar
 
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 1,190

Black and Green - '98 Civic DX Coupe
Team Honda
90 day: 64.83 mpg (US)
Thanks: 385
Thanked 166 Times in 113 Posts
Skinnier, lighter rear tires?

I have been reading some old posts, going back a couple years, on smaller and skinnier rear wheels. I still have a question about smaller and skinnier (thinking about tires). If I have 15" rims and plan to run 205/65-R15s on the front, how might I lighten or make more aero the rear tires using the same 15" rims? Can I run 175/65-R14s? It is possible to fudge the 14/15 thing a little, no? The Bridgestone Ecopia EP100s are just 14lbs at that smaller size. I thought I would maybe run the 205s on the front for taller gearing and the 175s on the back for aero, rotational mass, and easier fit behind skirts. Am I nuts or just wrong?


(Support Ecomodder.com & get rid of these annoying ads!)      
 
__________________


Black and Green will be rebuilt over decades as parts die--until it becomes a different car. Goal is only 60-70 mpg at posted speeds. I'm not trying for highest possible mileage.

Calculators: standard deviation, Ohms Law, & drag HP losses.
  Reply With Quote
Old 05-23-2011, 02:57 AM   #2 (permalink)
ooo ooo ooo ah ah ah
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 7,357

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

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

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

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

Moon Unit - '98 Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 636
Thanked 848 Times in 591 Posts
Quote:
It is possible to fudge the 14/15 thing a little, no?
Seriously? Then I'd go with "nuts".
__________________


  Reply With Quote
Old 05-23-2011, 12:38 PM   #3 (permalink)
Pishtaco
 
SentraSE-R's Avatar
 
Join Date: Jun 2009
Location: Bay Area, California
Posts: 1,278

Clean Green Toaster Machine - '06 xB
90 day: 45.81 mpg (US)
Thanks: 39
Thanked 193 Times in 127 Posts
You can't stretch 14" tires on 15" wheels, if that's what you're thinking. You'd have to buy 14" wheels, and you'd likely never make up the wheel cost in fuel savings.

You could go with 195 or 185 width tires in the rear, 60 or 65 profile, on your 15" wheels, but I wouldn't do it. There's minimal benefit mpg-wise, from the swap. Offsetting those questionable benefits, you're changing your car's aerodynamics, giving it a nose-up stance that might lift dangerously in cross- and headwinds. The skinnier rears might adversely affect emergency maneuvers. You'd be seriously mismatched if you had to replace a front flat with one of your rears, risking transmission damage driving the car.
__________________
Darrell

Boycotting Exxon since 1989, BP since 2010
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac? George Carlin
Mean Green Toaster Machine
49.4 mpg avg over 30,375 miles. 176% of '08 EPA
Best flat drive 94.5 mpg for 10.1 mi
Longest tank 1033 km (642 mi) on 10.56 gal = 60.8 mpg
Clean Green Toaster Machine
45.8 mpg over 2235 miles, 164% of '08 EPA
  Reply With Quote
The Following User Says Thank You to SentraSE-R For This Useful Post:
California98Civic (05-23-2011)
Old 05-23-2011, 12:39 PM   #4 (permalink)
EcoModding Apprentice
 
Join Date: Apr 2011
Location: Houston
Posts: 228
Thanks: 0
Thanked 20 Times in 16 Posts
I think the handling might get really wacky, and not in a good way.
  Reply With Quote
Old 05-23-2011, 04:00 PM   #5 (permalink)
Master EcoModder
 
Vekke's Avatar
 
Join Date: Jan 2009
Location: Nummela (Finland)
Posts: 629

Siitin - '98 Cordoba Vario
90 day: 58.56 mpg (US)

Starppa - '96 Starlet
90 day: 35.06 mpg (US)

Aeroscania - '97 P94D 260
90 day: 9.35 mpg (US)

VW Lupo 3L --> 2L - '00 Lupo 3L
Diesel
90 day: 66.4 mpg (US)
Thanks: 76
Thanked 152 Times in 73 Posts
I would go 185/60R15 on the rear. When you put smaller diameter tires on rear you have to adjust your stace. So you need to get lowering springs on the front.

I have 175/80R14 on the front and 175/70R14 at the rear. They are even different make. Last summer I had even 165/70R13 at the rear and had no problems with normal driving. My cars front is lowered 60mm and at the rear I have -30mm lowering springs.
__________________
www.tuneko.com
Less drag = Less fuel
  Reply With Quote
The Following User Says Thank You to Vekke For This Useful Post:
California98Civic (05-23-2011)
Old 05-23-2011, 04:27 PM   #6 (permalink)
60+ mpg at posted speeds
 
California98Civic's Avatar
 
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 1,190

Black and Green - '98 Civic DX Coupe
Team Honda
90 day: 64.83 mpg (US)
Thanks: 385
Thanked 166 Times in 113 Posts
Great advice guys. If I went with 185/60-R15s on the rear, I could get LRR Pirellis, get a net weight loss from my current cheapies, get the benefit of LRR, and taller gearing through 205/65s on the front. I'll have to think about it more though, because while lowering springs are in my plans, I was not anticipating that cost just now.
__________________


Black and Green will be rebuilt over decades as parts die--until it becomes a different car. Goal is only 60-70 mpg at posted speeds. I'm not trying for highest possible mileage.

Calculators: standard deviation, Ohms Law, & drag HP losses.
  Reply With Quote
Old 05-27-2011, 09:26 AM   #7 (permalink)
Master EcoModder
 
PaleMelanesian's Avatar
 
Join Date: Dec 2007
Location: Texas
Posts: 1,479

PaleCivic - '96 Civic DX Sedan
Team Honda
90 day: 74.33 mpg (US)
Thanks: 148
Thanked 138 Times in 97 Posts
I believe there are a number of good LRR tires available in the OEM size 185-65-14. These include the Insight-1 RE-92's. That's where I'd go, and match front and rear for simplicity.

tirerack lists 8 LRR in this size, including the Goodyear Assurance FuelMax. I have those on my Odyssey and LOVE them.


(Support Ecomodder.com & get rid of these annoying ads!)      
 
__________________
- - - - -Best 11-mile commute: 105 mpg
- - - - -Best tank: 88.5 mpg / 1133 miles
  Reply With Quote
Reply  Post New Thread

Thread Tools





Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2012, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com