Aftermarket LRRs?

[mamiata1]

Has anyone mounted aftermarket LRRs on custom wheels here? I'm thinking about some Sparco 18 LB wheels in a 16 x 7 and 205/50-16 LRR tires. I'm thinking they might be worth 3 to 5% percent in fuel economy. Right?

Also who makes the best LRRs in terms of fuel savings? Most manufacturers don't even mention a number.

[Fiesta_Mafia]

What are LRR's?


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[Audrey]

Low Resistance Rubber? Random guess is random.

You may have luck in the tire section of the forums too. (:

[Sterno]

Low Rolling Resistance

[billnchristy]

LRRs are good for some increases. My Prius came stock with Avid S33s and we put Primacy MXV4s on when they wore out after 33k miles. The MXV4s are NOT LRRs and we went from 46-48mpg to 44-46mpg.

So we can surmise that the tires were good for at least 2mpg in the Prius.

Will the Fiesta's go up by 2? Probably close. With the Prius it was nearly 5% change so you are looking around 1.5-1.6ish.

Now the question is, is it worth it?

Goodyear fuel max are considered among the best and they are $124 in your size versus $91 for stock tires.

This is $132 more.

Assuming 33mpg average jumping up to 34.5 will get you 15 more miles on a tank of gas (10 gallons for ease of math).


If the tires last 45k miles you will save 59 gallons of gas.

At current prices thats $194 so they will save you $60 over the life of the tire.

So it is "worth it" and I am sure gas will go up, but you can probably see that isn't worth fretting over so much.

PS, my new tires have amazing grip and wet weather performance, my LRRs were horrible in the rain.

[mamiata1]

Thanks for the information. I know it probably sounds silly but what I would like to do, in addition to the LRRs with a slightly larger diameter than stock, is to maximize fuel economy. So I already have an Injen CAI and plan on a catback possibly the Flowmaster unit. Then maybe also add a front splitter and air deflectors like on the SFE. I'm not even sure if a splitter like the Bojix would help or hurt MPGs. I probably can't expect more than about a 5% improvement but I would settle for that.

[billnchristy]

Not sure how much hurt the small increase will get you but do know it will slightly throw off your odo which will throw off your mpg readings.

Size/diameter and all.

When my S33s died I was getting 55mpg, presumably due to the utter lack of resistance from no tread plus the tire was that much smaller.

Also, something of note, on Prii with 17" wheels people note a drop of 1-2mpg so its possible that the 15" stock Fiesta will get very slightly better eco than the 16"

Light wheels will help combat that though.

[mamiata1]

If I go with the 205/50-16 vs. the 185/60-15 that came stock there is only a little over 1% change in diameter which can easily be calculated in when figuring gas mileage plus that represents a minimal change in what the odometer will read. I know the 16" wheels I'm looking at are 18 LBS and I'm guessing the stock 15" aluminum wheels are similar but don't know the actual weight.

The truth will be told during fillups and calculating the true mileage. I've found from experience on our 2009 Focus that the trip computer tends to be about 10% more optimistic than actual MPGs.

[billnchristy]

Originally Posted by mamiata1

If I go with the 205/50-16 vs. the 185/60-15 that came stock there is only a little over 1% change in diameter which can easily be calculated in when figuring gas mileage plus that represents a minimal change in what the odometer will read. I know the 16" wheels I'm looking at are 18 LBS and I'm guessing the stock 15" aluminum wheels are similar but don't know the actual weight.

The truth will be told during fillups and calculating the true mileage. I've found from experience on our 2009 Focus that the trip computer tends to be about 10% more optimistic than actual MPGs.

Yeah they all are a little. The Prius is about 5% the Fiesta is around 2-3% but more varying. Sometimes the Fiesta is almost dead on, other times its 2-3mpg off. The Prius is always optomistic the same amount.

[mamiata1]

After a little more research it seems the Bridgestone Ecopias are the exact same diameter as the Kumho Solus KH25s that came with the car (24.1").

Also I found an old Tire Rack test where they compared several Low Rolling Resistance tires to the stock tire and the Ecopias were a little better than a 4% improvement in MPGs. Not a lot but at least it's something. A few of the so called LRRs actually did worse than stock.