I am going on a road trip to Cali and I was told that my 17's will get better gas mileage than my stock 15's. I know 15's will get me better times at the track and street but I thought the rolling diameter of 17's would yield me WORSE gas mileage than 15's. My friend told me that the inertia of the 17's and that fact that they travel further per revolution would help. Also he said that although 15's will get better times, 17's will get higher mph's on a drag strip. Can you guys clarify?

 

17's will get u better milage, but will also throw your speedometer off a big. i believe its due to the overall radius. but it also depends on your tire sizes

 

205/40ZR-17

 

If them 15's get you better times I'd think they will give you better gas milage because they are lighter.
I'm saying this base on my assumption that the outside diameter of your tires are the same.

 

it takes more gas on bigger rims, because it takes more power on your car to make the rim turn in a full circle. if those 17s are heavy, its better to throw back on your stock rims. unless you really don't care in loosing a couple miles here and there.

 

the 17's are almost the same as the stockers +- 1lbs

 

ok break it down... what is the weight of the rims. a stock 98-01 gsr 15x6" rim is 16.3 lbs a light wieght spoon sports sw388 15x6.5 is 8.6lbs. ok with that said rotational mass slows you down so you would be quicker and saving fuel with the spoon sports rim. now a 17 inch rim (rota attack for example 17x7") weights 15.5lbs. so you wouldn't notice any difference in fuel economy. now I am running 18" motegi mr7's and they weight a ton 27.5 lbs. now this is each. so stock wheel weight was approxamately 60lbs I am approx. 120. my fuel economy dropped by 20 mpt(miles per tank) well that is what I noticed. Just think about the weight. Good shopping.

 

btw i gotta give props to this site for that

http://www.wheelweights.net/

doesn't have every wheel but it sure got the point across

 

Okay... i could be way off here but if you have the same total wheel/tire diameter with both the 15" and 17" setup, and the weight is pretty much the same as well, then you will probably not see any significant change in your mileage. THe moment of inertia is dependent on the wieght of your rim and like they said, if you have a lightweight 17" then it won't really matter now will it? So again, if those two characterisitics are the same, then you shouldn't be too concerned with it, and just roll on whatever you prefer. I'd be more concerned about what cd's to take, but thats just me n my 2 cents

 

I don't think it really matters if your 17's are lightweight and the same rolling diamter (or really close) as the stockers.. not sure where your from but I'm going to assume its going to be all or mostly highway miles... after you get rolling it doesn't make much of a difference... I've rolled from so cal to nor cal w/ both my cars before.. driven w/ stock wheels on both cars before and also driven w/ 5Zigens on 1 car and SSR's on the other and mileage was pretty much the same.. it was all highway (I5 from SO Cal to Nor Cal) trips and I honestly didn't notice much of a difference because it was all highway..

I made this trip MANY MANY MANY times as I would go to college in Nor Cal but my ex lived in So Cal.. it was pretty much the same... if you want to roll your rims go ahead.. but the tires on your 17's are probably mor expensive so if your putting A LOT of miles (like driving from east coast to CA) then maybe you want to put on your slower wearing stockers... but I wouldn't even trip about mileage because assuming you have a light weight rim it doesn't make much of a difference...

 

17 will get better gas milage. the 17s will put you at a lower rpm at cruising speed meaning less gas will be burned.

its like this when you have 15s on say you only get to 35 in first gear. but when you have 17s on you will get to maybe 40 or so. think of that in all your gears. so at 80 mph in fifth gear you will be at lets say 4500 with your 15s on but with the 17s on you will be at lets say 3500. that means you save gas

 

w/ the stock 195/55/15:
Sidewall: 4.2"
Radius: 11.7"
Diameter: 23.4"
Circumference: 73.7"
Revs/mil: 860.0

w/ 205/45/16:
Sidewall: 3.6"
Radius: 11.6"
Diameter: 23.3"
Circumference: 73.1"
Revs/Mi: 867

w/ 205/40/17:
Sidewall: 3.2"
Radius: 11.7" (Identical to stock)
Diameter: 23.5" (.1" more)
Circumference: 73.7" (identical to stock)
Revs/mi: 860.0 (identical to stock)

I don't really see a difference on paper/stats.. nor did I see a difference in real life (when I drove from So Cal to Nor Cal between college and visiting my Ex-gf)...

 

Hmm.. Good facts. I see.

 

No difference. Once you are rolling the only thing that will affect you is tire pressure. Higher pressure will get you better gas mileage.

I have put over 7000 road trip miles on my gsr in the last 1.5 years.

 

Dude, i'll give u the extra 10 bucks you'll be loosing..LOL geez...

 

I was just curious...it it would have made a big difference I would have taken the 30 min to swap out my rims...