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If highway mileage for the Focus ST becomes the concern, one can always get a set of 16" wheels and narrower tires to help reduce the rolling resistance hit on mileage as well as offering some unsprung weight savings. The ride would get a bit "cushier" though, and in some areas of the country with horrible roads, may not be a bad idea.
 
If highway mileage for the Focus ST becomes the concern, one can always get a set of 16" wheels and narrower tires to help reduce the rolling resistance hit on mileage as well as offering some unsprung weight savings. The ride would get a bit "cushier" though, and in some areas of the country with horrible roads, may not be a bad idea.
"Cushier" ride only occurs if the sidewall aspect ratio is increased and the tire pressure is reduced, but if you are keeping the same outside diameter both of these would be accomplish with 16s, although I would actually only recommend dropping it to 17s as it would look much MUCH better than 16s.
 
"Cushier" ride only occurs if the sidewall aspect ratio is increased and the tire pressure is reduced, but if you are keeping the same outside diameter both of these would be accomplish with 16s, although I would actually only recommend dropping it to 17s as it would look much MUCH better than 16s.
True. I am seriously considering buying 17s with a 215/50-17 tire to get a bit more cushion as our roads are rather rough and to bump up mileage just a bit. 16s would be good for a snow tire set though, as lower profile snow tires are $$$$$
 
Are you guys only using the trip computer or are you actually calculating the mileage? I never trust the computer due to the fact I have never had one that reads accurately.
 
17" Wheels and tires should get slightly better mileage than 18s as they will generally have a narrower tire width and lighter rim whose outer rim mass is closer to the center of the tire, making it slightly easier to spin up. Any difference though will likely be quite small. They shouldn't get worse mileage unless the tire OD is significantly smaller, causing the tire to make more revolutions to travel the same distance.

Also, I remember seeing a test somewhere where someone went from low profile tires with a very large rim to a slightly smaller rim with not so low profile tires, and the car's track performance actually improved since it wasn't so harsh. Not sure which tires were used though.
 
Grass Roots Motorsport did an excellent comparo / write up on this topic. Might be available on line.
 
Grass Roots Motorsport did an excellent comparo / write up on this topic. Might be available on line.
This one?
Speed Holes: Grassroots Motorsports Magazine Articles

Kind of an interesting result, I wonder if they did one on fuel mileage vs. tire size too.

Edit: Only thing is the tire sizes they chose in the article weren't the same OD and probably messed a bit with their results as acceleration and braking distances would be affected:

16" Tire selection: 205/55R16 ~24.8" OD
17" Tire selection: 225/50R17 ~25.8" OD
18" Tire selection: 225/50R18 ~26.9" OD

Not sure why they would select tires with such different ODs...not only would they skew the results, you would think they would rub horribly. The aspect ratios should have been changed to compensate.
 
The differences in the emissions equipment can really affect MPG. We really won't know for sure until the EPA releases its numbers once they are done with all their fiddling. Even then, real-world numbers may be slightly different.
 
I'll be a little disappointed if the Focus ST is only sporting 21 city and 31 highway like I saw in a few places. My '09 Cobalt SS is rated 22 city and 30 highway, and I avg 29.3mpg mostly doing city. My avg speed is 36.6 mph. So I do hope the Focus ST can best that because I want something better on gas to allow me to retire my Cobalt from daily use.
 
Breath slowly. That's better.

This may be old news but I noticed that when the UK pricing came out they also stated the ST gets 39.2 UK MPG which is 32.6 US MPG. Not sure how they do testing in the UK though or how US emission requirements etc ... may effect this.

Focus ST to start from £22k - BBC Top Gear
Ford Releases UK Pricing on New 247hp Focus ST Hatchback and Estate Models - Carscoop

"Ford says that the new Focus ST returns a combined fuel economy of 39.2mpg UK and CO2 emissions of 169g/km, a 20 per cent improvement over its predecessor."

(emphasis was mine)

So, we have two stories on this, and have no idea how it relates to the US ratings. If they're holding back this long, either the numbers are going to be unbelievably good, or disparaging.

If it got 33 mpg highway only, that's still 5 mpg better than a GTI-R.
 
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