nmadole Posted November 3, 2014 Share Posted November 3, 2014 (edited) I recently had the PCM Update (letter set to be sent out this month) and put snow tires on my 2013 ford fusion Hybrid. I frequently take the same 2.5 hour trip to my home town. I have taken the trip probably 50 times in the last 29,000 miles In similar weather conditions with my stock 18" tires (prior to the update) I would get around 40 MPG Last night I took the drive for the first time since the update/ snow tires were put on and I ended up at 45 MPG ..... I am utterly confused FIELD SERVICE ACTION NUMBER: 14E02 Edited November 3, 2014 by nmadole Quote Link to comment Share on other sites More sharing options...
akirby Posted November 3, 2014 Share Posted November 3, 2014 Snow tires probably have lower rolling resistance. Quote Link to comment Share on other sites More sharing options...
nmadole Posted November 3, 2014 Author Share Posted November 3, 2014 Snow tires probably have lower rolling resistance. Everything I have ever heard about snow tires is they lower MPG.... They are Bridgestone Blizzak You think snow tires could actually increase my MPG by almost 13%? Quote Link to comment Share on other sites More sharing options...
twintornados Posted November 3, 2014 Share Posted November 3, 2014 What size are the snow tires? Did you "minus 1" the size? Quote Link to comment Share on other sites More sharing options...
akirby Posted November 3, 2014 Share Posted November 3, 2014 Living in Atlanta I don't know much about snow tires but they usually are narrower which would help. But to twintornados point - are they the same size as the stock tires? If not then it could be the odometer that's off not the fuel usage. 1 Quote Link to comment Share on other sites More sharing options...
twintornados Posted November 3, 2014 Share Posted November 3, 2014 Well, to be clear akirby, "minus 1" brings the rim diameter down but keeps the overall diameter of the tire the same while narrowing the tire so that it cuts through the slop and snow instead of riding up on top of it...I actually did a "minus 3" on my Lincoln as it came with the optional 20" tires and I am now running 17" tires for the winter...but, technically, I did a "minus 1" since the stock size is an 18"....overall diameter measures the same for the optional 245/50-20, standard 245/60-18 and the winter tires I went with at 245/65-17....But I am willing to bet that most drivers just swap on winter tires of the same size as the "three season" radials they just took off.... Quote Link to comment Share on other sites More sharing options...
akirby Posted November 3, 2014 Share Posted November 3, 2014 I know what plus 1 or minus 1 means. I was referring to your first question on the size of the snow tires. Quote Link to comment Share on other sites More sharing options...
twintornados Posted November 3, 2014 Share Posted November 3, 2014 I know what plus 1 or minus 1 means. I was referring to your first question on the size of the snow tires. Ok...wasn't sure....hence my original question of what size he put on the car....I am interested to see if my mileage goes up or down, just put my new tires/rims on 11/1....will see if the mileage is affected.... Quote Link to comment Share on other sites More sharing options...
nmadole Posted November 3, 2014 Author Share Posted November 3, 2014 My stock rims are 18", but winter rims are 17"; but the diameter of the tire is exactly the same. The odometer should not be affected Quote Link to comment Share on other sites More sharing options...
twintornados Posted November 3, 2014 Share Posted November 3, 2014 My stock rims are 18", but winter rims are 17"; but the diameter of the tire is exactly the same. The odometer should not be affected Ok cool....since you "minus 1" sized the snows, while the diameter is the same (thus not throwing the odometer off), the contact patch is smaller, producing less rolling resistance per tire...I am impressed with the gain...I will keep an eye peeled on my MPG as well...should be interesting. Quote Link to comment Share on other sites More sharing options...
akirby Posted November 3, 2014 Share Posted November 3, 2014 Ok cool....since you "minus 1" sized the snows, while the diameter is the same (thus not throwing the odometer off), the contact patch is smaller, producing less rolling resistance per tire...I am impressed with the gain...I will keep an eye peeled on my MPG as well...should be interesting. Why would the contact patch be smaller if the tire is the same diameter and width? Quote Link to comment Share on other sites More sharing options...
twintornados Posted November 3, 2014 Share Posted November 3, 2014 (edited) Why would the contact patch be smaller if the tire is the same diameter and width? The overall diameter of the tire remains the same, but he dropped to a 17" rim...for the diameter of the tire to remain the same, the aspect ratio will change and will make the tire taller and slightly narrower...granted, the "section width" is only incrimentally smaller, but it is narrower, in some cases as much as 1" narrower....I suspect that the re-flash may have more to do with it...but you cannot argue with a 5 MPG gain... PS: In my case, I went from a 245/50-20 to a 245/65-17...the tread width is almost 1" narrower, but the overall diameter of the tire is the same. Edited November 3, 2014 by twintornados Quote Link to comment Share on other sites More sharing options...
akirby Posted November 3, 2014 Share Posted November 3, 2014 245 mm = 245 mm tread width. How can it be 1" narrower? Quote Link to comment Share on other sites More sharing options...
nmadole Posted November 3, 2014 Author Share Posted November 3, 2014 (edited) My 17" Tires = 215/55/17 My 18" Tires = 235/45/18 Looks like the old tires are wider .... 8.5% wider to be exact 5MPG is alot tho ... Edited November 3, 2014 by nmadole Quote Link to comment Share on other sites More sharing options...
twintornados Posted November 3, 2014 Share Posted November 3, 2014 (edited) 245 mm = 245 mm tread width. How can it be 1" narrower? Wrong... From Wikipedia for a description of how tires are measured... http://en.wikipedia.org/wiki/Tire_code 3-digit number: The "nominal section width" of the tire in millimeters; the widest point from both outer edges (side wall to side wall). The tire surface that touches the road usually has smaller width. /: Slash character for character separation. 2- or 3-digit number: The "aspect ratio" of the sidewall height as a percentage of the total width of the tire. If the information is omitted, it is assumed to be 82% (if written, it should be like xxx/82). If the number is larger than 200, then this is the diameter of the entire tire in millimeters. An optional letter indicating construction of the fabric carcass of the tire: B: bias belt (where the sidewalls are the same material as the tread, leading to a rigid ride) D: diagonal R: radial if omitted, then it is a cross-ply tire 1- or 2-digit number: Diameter in inches of the wheel that the tires are designed to fit. There is the rare exception of metric-diameter tires, such as the use of the 390 size, which in this case would indicate a wheel of 390 mm in diameter. Few tires are made to this size presently. The number may be longer where a half-inch size is used, for example many heavy transport trucks now use 22.5-inch tires.[6] Edited November 3, 2014 by twintornados Quote Link to comment Share on other sites More sharing options...
akirby Posted November 3, 2014 Share Posted November 3, 2014 What's wrong about it? 245 mm = 245 mm. You must be thinking of the sidewall height that changes with the aspect ratio, not the tread width. Quote Link to comment Share on other sites More sharing options...
twintornados Posted November 3, 2014 Share Posted November 3, 2014 (edited) What's wrong about it? 245 mm = 245 mm. You must be thinking of the sidewall height that changes with the aspect ratio, not the tread width. Kirby...you are confusing "section width" vs "tread width"...my 245/65-17's are approx. 1" narrower than my 245/50-20's...don't know why...but it is....you are right, the 245mm number is the same, but....the aspect ratio makes the tire taller to offset the rim being smaller....now, maybe it is because the 20's are Pirellis and the 17's are Goodyears...but my tape ruler does not lie....the contact patch IS 1" smaller....his tires are even more pronounced due to the section width number being smaller... ADD ON: I was originally going to go with Tirerack's recommendation of a 235/65R-17 but the overall diameter was 1/2" shorter than the 245/65-17 and the 245/50-20..... Tire measurements are a crazy science, and I will concede that your calculation SHOULD make sense.....but we are talking tire measurements....I can remember back to the ole H78-15s on my mothers station wagon in the '70's....now THAT is a confusing measurement system for sure... Edited November 3, 2014 by twintornados Quote Link to comment Share on other sites More sharing options...
akirby Posted November 3, 2014 Share Posted November 3, 2014 Ok, so it's section width. But since nobody publishes the width of the actual tread contact patch that's all you can go by. My guess is the shoulder of the tire is wider on one than the other. 1 Quote Link to comment Share on other sites More sharing options...
twintornados Posted November 3, 2014 Share Posted November 3, 2014 Ok, so it's section width. But since nobody publishes the width of the actual tread contact patch that's all you can go by. My guess is the shoulder of the tire is wider on one than the other. Quote Link to comment Share on other sites More sharing options...
expresspotato Posted November 7, 2014 Share Posted November 7, 2014 This thread quickly turned into a thread about tires for 18 posts... But there is *another* PCM update? Quote Link to comment Share on other sites More sharing options...
nmadole Posted November 7, 2014 Author Share Posted November 7, 2014 This thread quickly turned into a thread about tires for 18 posts... But there is *another* PCM update? Yeap, letters will be going out this month Quote Link to comment Share on other sites More sharing options...
expresspotato Posted November 30, 2014 Share Posted November 30, 2014 Anyways took it into the shop for a PCM update the other day along with a few TSB's here and there (what else is new). Didn't help me one bit and the consumption is quite poor in the winter and they could really work on the logic / algorithm of it... - The engine races to fill the battery consuming gas all the while and once it gets to 100% its on for heating the cabin... Probably would have made a lot more sense to just let it fill the battery at a less aggressive pace, if the engine is -10C you know you're not going to be turning it off anytime soon because its now at 50C. - Again the engine is on only to heat the cabin and you stomp on the throttle. Its only using 1/3 electric and 2/3rd gas oblivious to the fact its going to get back up to 100% and stop charging in about 30 seconds after the throttle is released. It should have used all the electricity it could instead of the irreplaceable gas. - Its really weird only giving it half the electric response when the cabin isn't fully warmed up (or some other logic they're using). Turning off the climate gives it back up to the 2nd notch of EV... Happened with the first PCM update last year. They're version of warmed up and mine don't seem to line up sometimes I'll make it all the way to work about an hour away and still only have half of ev power. - Not really MPG related but PCM related its been two years now and the transition to ICE from EV is more rough for sure. Its as if it gives up starting the ICE and cuts off the electricity a bit too early. Its a whole jarring experience. - Although this isn't PCM related: The second heating / cooling loop must be crazy inefficient. Although I hate the Prius you can sit for a good 10 minutes before the ICE will come back on even with the fan blowing... Fusion hybrid? ICE comes on after about a minute and a half maybe two at most. Quote Link to comment Share on other sites More sharing options...
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