05-23-2011, 01:38 AM
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#1 (permalink)
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Cyborg ECU
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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?
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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.
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05-23-2011, 02:57 AM
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#2 (permalink)
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(:
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Quote:
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It is possible to fudge the 14/15 thing a little, no?
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Seriously? Then I'd go with "nuts". |
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05-23-2011, 12:38 PM
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#3 (permalink)
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Pishtaco
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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.
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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
49.5 mpg avg over 53,000 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
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05-23-2011, 12:39 PM
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#4 (permalink)
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EcoModding Apprentice
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I think the handling might get really wacky, and not in a good way.
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05-23-2011, 04:00 PM
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#5 (permalink)
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Mechanical engineer
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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.
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05-23-2011, 04:27 PM
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#6 (permalink)
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Cyborg ECU
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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.
__________________
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.
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05-27-2011, 09:26 AM
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#7 (permalink)
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Hypermiler
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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.
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11-mile commute: 100 mpg - - - Tank: 90.2 mpg / 1191 miles
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