20's and mpg?
10-31-2007, 01:14 AM
#41
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You were the one who brought up acceleration man. Also you keep forgetting to see here is that the 20" wheel combo and the stock combo are THE SAME DIAMETER so your theory is thrown out the window. I got better MPG with my stockers than the 20's that were the same diameter. You are some what correct on it takes less effort to keep an object moving but if an object weighs more it will take more effort to keep it moving unless you're going down hill.
Please people read from the begining,
Im not saying anything about accelration,
Smaller diameter rim/tire combo gets better acceleration but bad MPG at 65 mph on the freeway for long periods of time,
What im saying is a larger diameter rim/tire combo gets better mpg at 65mph on the freeway for long periods of driving time. So if you take a 500mile road trip, then you would benifit from a large diameter tire. but at the same time they suck at acceleration.
My point is Larger = better MPG and shorter = Less MPG at freeway speed at 65mph
10-31-2007, 08:34 AM
#42
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Ok ok. hold up. the conversation just got lost.
Please people read from the begining,
Im not saying anything about accelration,
Smaller diameter rim/tire combo gets better acceleration but bad MPG at 65 mph on the freeway for long periods of time,
What im saying is a larger diameter rim/tire combo gets better mpg at 65mph on the freeway for long periods of driving time. So if you take a 500mile road trip, then you would benifit from a large diameter tire. but at the same time they suck at acceleration.
My point is Larger = better MPG and shorter = Less MPG at freeway speed at 65mph
Please people read from the begining,
Im not saying anything about accelration,
Smaller diameter rim/tire combo gets better acceleration but bad MPG at 65 mph on the freeway for long periods of time,
What im saying is a larger diameter rim/tire combo gets better mpg at 65mph on the freeway for long periods of driving time. So if you take a 500mile road trip, then you would benifit from a large diameter tire. but at the same time they suck at acceleration.
My point is Larger = better MPG and shorter = Less MPG at freeway speed at 65mph
I really think you're the one that is lost in this conversation. You have mention at least in three different posts talking about acceleration with big gear/tire combos. LOL Maybe you need to go back and re-read your posts. What everyone in this thread is trying to get you to see is rotating mass being the key here not tire diameter because they are the same.
Last edited by 1ORANGEWS6; 10-31-2007 at 11:13 AM.
10-31-2007, 09:37 AM
#44
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So much for the scientific approach here. You can't scientifically change 2 (or more) factors at a time on a test and expect to understand the results (ie. wheel size and tire diameter). We are talking apples and oranges here. Wheel size has absolutely no effect on tire diameter in which your whole mpg argument seems to be based on. Also mph will be a factor in the mpg's.
As for your test with 2 trucks, that won't work either, using 2 different trucks throws another variable into the mix. Since it's no secret that 2 engines even though built the same most likely will not get exactly the same fuel mileage.
The fact is just increasing wheel diameter and keeping tire diameter equal will make little mpg difference at a constant speed. Average mpg however, will suffer due to the added power needed to accelerate the additional mass.
Now when increasing tire diameter independent of wheel size it is possible to increase steady speed mpg some, but it is also relative to the powerband/efficiency range of the engine. Once the tire gets too big you won't have enough power to maintain speed. Also with increased tire diameter you will generally have another increase in mass affecting average mpg.
As for your test with 2 trucks, that won't work either, using 2 different trucks throws another variable into the mix. Since it's no secret that 2 engines even though built the same most likely will not get exactly the same fuel mileage.
The fact is just increasing wheel diameter and keeping tire diameter equal will make little mpg difference at a constant speed. Average mpg however, will suffer due to the added power needed to accelerate the additional mass.
Now when increasing tire diameter independent of wheel size it is possible to increase steady speed mpg some, but it is also relative to the powerband/efficiency range of the engine. Once the tire gets too big you won't have enough power to maintain speed. Also with increased tire diameter you will generally have another increase in mass affecting average mpg.
10-31-2007, 11:16 AM
#47
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....This discussion has went to **** quickly. LOL....I think I'll take my 32X11.50 on 16's and my 140 MPG and drink some Coronas until this all makes sense.
11-05-2007, 07:57 AM
#48
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I swapped out the 285-50-20's for my stock 265-70-17s which turns out to be .4" in diameter larger than the 20's and I went from 14.9 city / 17.1 hwy to 17.5 city / 19.7 hwy doing about 70 mph. I was getting a little over 20 and 21 mpg until I started high long hill stretches. Maybe I guess the larger diameter tires do get better mpg. Oh and I borrowed a scale to weight the tires. The 20's weighed 29.x lbs more than the stockers and the stockers were 68 lbs. I still think in this case that the extra rotating mass played a huge difference in the mpg.
11-05-2007, 12:08 PM
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I swapped out the 285-50-20's for my stock 265-70-17s which turns out to be .4" in diameter larger than the 20's and I went from 14.9 city / 17.1 hwy to 17.5 city / 19.7 hwy doing about 70 mph. I was getting a little over 20 and 21 mpg until I started high long hill stretches. Maybe I guess the larger diameter tires do get better mpg. Oh and I borrowed a scale to weight the tires. The 20's weighed 29.x lbs more than the stockers and the stockers were 68 lbs. I still think in this case that the extra rotating mass played a huge difference in the mpg.
The 29lbs extra per tire/rim does.
