Last post on Mar 31, 2013 at 7:52 PM
You are in the Ford Escape
What is this discussion about?
Mazda Tribute, Ford Escape, SUV
#195 of 235 Re: Tire Size [mschmal]
Nov 22, 2006 (9:45 am)
"the second number is the diameter number and is a ratio."
The second number is the sidewall height as a percentage of the width. Therefore the 245/70-16 tire/wheel total diameter = 29.50" and the 235/70-16 diameter = 28.95" The difference is 1.9% which I rounded to 2%
A 245/65-16 tire, if available, would be a negligible change as far as diameter/circumference.
#196 of 235 Re: Tire Size [steve_]
Nov 22, 2006 (10:12 am)
Thank you Steve, and everybody, for your input. I went to that 1010 site and came up w/this chart as a comparison:
http://www.1010tires.com/TireSizeCalculator.asp?action=submit (if that works).
235 measurements 245 measurements in bold, couldn't space 'em out
Section Width: 9.25 in 235 mm 9.64 inches/245mm
Rim = 16" 406.4 mm Same
Overall Diameter: 28.95 in/735.33 mm 29.50 in/749.3 mm
Sidewall Height: 6.47 in/164.33 mm 6.75 in 171.45 mm
Radius: 14.47 in/367.53 mm 14.75 in 374.65 mm
Circumference: 90.94 in/2309.8 mm 92.67 in 2353.8 mm
Revs per Mile: 718.4 705.0
Actual Speed: 60 mph 58.8
Speedometer Difference: ---- 1.900% too slow
Diameter Difference: ------ 1.87%
So, my tires are a bit larger by a few measurements here and there, not just in tread that hits the pavement (245mm), therefore giving me less revolutions per mile, I guess my Tribby is working harder to make itself go, which would effect fuel economy. I'm hoping it comes back up a bit after the next o/c, tune up, etc. I liked getting about 20 mpg, however I suppose I really can't tell since my odometer must be a bit off as well??
#197 of 235 Re: Tire Size [chimpsnest]
Nov 22, 2006 (10:23 am)
sorry, my comments were aimed towards hybrid owners where there has been a lot of discussion about FE and tire rolling resistance.....from my non-hybrid SUV experience, you have upgraded by going to the michelins and should see several benefits (wet/dry traction, road noise, etc.) for the cost of a few miles per gallon
#198 of 235 Re: Tire Size [chimpsnest]
Nov 22, 2006 (3:27 pm)
do those michelins have a 700 treadwear rating?
if they do(ok, they do), i have had the conti's on our escape and have the cross terrains on my explorer.
my explorer experienced a slight bump in mileage after putting on the cross terrains.
bear with me a bit.
go to tirerack and look up how many revolutions per mile for each tire. this will give you the true difference of the size difference if the tires.
not all the tires of the same size are actually the same size. i just replaced the conti's on the escape with goodyear tripletreads. they are noticeably larger than the conti's they replaced. the conti's are also a very light tire. you can get those numbers from tirerack, too.
run about 20 miles or so on a highway with measured miles to determine your odometer accuracy. the cross terrains measure 19.8 on the trip odometer over 20 measured miles.
i have done this several times.
so are the cross terrains a lot quieter?
for me, the cross terrains are not that great in bad weather.
#199 of 235 Re: Tire Size [explorerx4]
Nov 24, 2006 (10:27 am)
RE: 700 treadwear .... how would I find this out? It looks like you confirmed it?
RE: Revs per mile, I did the comparison at the 1010.com site and the 235's were around 718 rvs per mile and the 245's are 705 revs per mile (I believe, I'm going on a turkey rattled memory function right now, lol).
I did notice a difference in road noise, but my OEM's had 86K miles on them, I think ANY new tire I put on the Trib would reduce road noise that point.
I haven't noticed any slippage in rain and we have not had any snow yet.
I've got to find a measured mile, my OD and my trip OD never meshed anyway, they were off buy a tenth or two to start with. I'll talk to the dealer about it next time I'm in there.
#200 of 235 Re: Tire Size [steve_]
Nov 27, 2006 (7:12 am)
The 4% dif was because I used the wrong diameter, 14 in stead of 16. I was on TireRack.com and they have the equations but not a calculator. The example used a 14 inch tire and I mistakenly used that same number (in mm), thus suggesting a 4% mpg reduction instead of the correct 1.9%.
In either case, the outside diameter of the tire (not the rim) does change as the width changes given that the profile ratio stays the same.
Width x Aspect Ratio = Section Height
Section Height x 2 = Combined Section Height
Combined Section Height + Wheel Diameter = Tire Diameter
Example: 185/60R14 85H or 185/60HR14
185mm x .60=111mm
111mm x 2=222mm
222mm + 355.6mm(14")= 577.6mm or 22.74"
The first number is the width of the tire in millimeters, measured from sidewall to sidewall. To convert to inches, divide by 25.4 In the example above, the width is 185mm or 7.28".
The second number is the aspect ratio. This is a ratio of sidewall height to width. In the example above, the tire is 7.28" wide, multiply that by the aspect ratio to find the height of one sidewall. In this case, 185x0.60=111mm or 7.28"x0.60=4.36".
The last number is the diameter of the wheel in inches.
To figure the outside diameter of a tire, take the sidewall height and multiply by 2,(remember that the diameter is made up of 2 sidewalls, the one above the wheel, and the one below the wheel) and add the diameter of the wheel to get your answer.
#201 of 235 Re: Towing Capacity [tidester]
Nov 27, 2006 (2:12 pm)
Question - how do you put a tow hitch on a 2007 FEH? Apparently, this isn't available through FMC, even as an accessory. I don't want to tow anything - just want to mount a scuba tank rest for suiting up in comfort before a dive
#203 of 235 Re: Tire Size [chimpsnest]
Nov 28, 2006 (4:42 pm)
the 1010.com site is good for the basic information.
tirerack will show you the actual revolutions per mile for individual tires. the treadwear info is available there too.
like i said, nor all tires of the same size are actually the same size. i did a 30 measured mile run with my michelin equipped vehicle. it still registers 1% under(30 miles registered 29.7 on the odometer) after about 18k miles.
#204 of 235 Re: Towing Capacity [mecheng1]
Apr 20, 2007 (1:09 pm)
I am hoping to purchase a 2008 FEH, but I will have to install a tow hitch to carry a lift for my mother's scooter. Can anyone give me some basic info about the tow rating for a FEH?