Ride height difference??

[Mattsgt]

I was wondering if anyone knew if there was a difference in the step-in height (Height from floor of vehicle to ground) fir an Edge with 18" wheels vs. one with 17" wheels. You would think there would be, but none is listed in the material I have read?

[sim]

You are talking of a difference of 1" in the diameter of the wheel, then of course there is the possible difference in the wall height of the two types of tires. Of course the suspension will raise or lower the car a small amount depending on the amount of load you are carrying and where it is placed in the car, and it goes on from there. Realistically the step-in height is relatively insignificantly changed. I tried both 17" and 18" equipped models and couldnt tell any difference in the step in height, at 6' 3" i can just plant my butt on the seat and slide in without hassle with either model - if there is a difference, you cant perceive it. We bought the Edge with the 18" wheels and my wife's 80 yr old grandmother who cant walk so well was able to get in without much hassle!!

 

Besides the additional bling factor, and unfortunately probably a higher replacement cost when they wear down, the slightly larger wheels usually offer a slightly smoother ride over bumps, that is one advantage to them.

[Mattsgt]

You are talking of a difference of 1" in the diameter of the wheel, then of course there is the possible difference in the wall height of the two types of tires. Of course the suspension will raise or lower the car a small amount depending on the amount of load you are carrying and where it is placed in the car, and it goes on from there. Realistically the step-in height is relatively insignificantly changed. I tried both 17" and 18" equipped models and couldnt tell any difference in the step in height, at 6' 3" i can just plant my butt on the seat and slide in without hassle with either model - if there is a difference, you cant perceive it. We bought the Edge with the 18" wheels and my wife's 80 yr old grandmother who cant walk so well was able to get in without much hassle!!

 

Besides the additional bling factor, and unfortunately probably a higher replacement cost when they wear down, the slightly larger wheels usually offer a slightly smoother ride over bumps, that is one advantage to them.

 

Thanks for the help. The only reason I ask is that on our SEL, it has 18" wheels and my little kids have a hard time getting in and out, especially when its wet and slushy out. My SE is going to have 17's and when I get it I was going to swap the tires if it would help lower it a little bit. Once I get my SE, I'll just measure both of them, but I expect the difference to be minimal if at all.

[npggirl]

Thanks for the help. The only reason I ask is that on our SEL, it has 18" wheels and my little kids have a hard time getting in and out, especially when its wet and slushy out. My SE is going to have 17's and when I get it I was going to swap the tires if it would help lower it a little bit. Once I get my SE, I'll just measure both of them, but I expect the difference to be minimal if at all.

 

Just out of curiosity...Do they offer any side bars or step bars for the edge yet for that reason?

[mkaresh]

Changing the diameter of the tire will throw the speedometer and odometer off. Specifically, going to a smaller wheel will cause the odometer to accrue miles faster, depreciating your vehicle faster and using up the warranty faster. So I wouldn't do it.

 

That said, there is probably very little difference between the two. Anyone care to do the math?

[Zeus]

Changing the diameter of the tire will throw the speedometer and odometer off. Specifically, going to a smaller wheel will cause the odometer to accrue miles faster, depreciating your vehicle faster and using up the warranty faster. So I wouldn't do it.

 

That said, there is probably very little difference between the two. Anyone care to do the math?

 

I can do SOME math....but you probably won't get the answer you are looking for. I am also wondering if anyone is willing to take on this challenge.

 

My math = 2 + 2 is 4

[sim]

No sidesteps/bars yet, we asked and nothing out there so far. However we were told that people who create the aftermarket equipment such as the steps might well have bought an Edge to start taking it apart to fit in their products. Nothing from Ford for sure yet though.

 

As for the math, really its just the difference of 1" in diameter in the rim and a slightly different tire - which is just under 1" in height on the vehicle overall. However there could be just as much spring contraction based upon the weight of and in the vehicle and its distribution. Looking at the rims and tires, assuming no compression of the wheel walls the 18" rim is 1" larger than the 17", the tires are P235/65 R17 and P245/60 R18, which when added to the rim would result in 0.77" difference in overall diameter of the rim and tire due to the lower aspect ratio and wider width of the 18" tire. When you calculate out the circumference of each of the tires the 17" gives 6.03', the 18" is equal to 6.23', difference of 0.2' (~2.5"). When you compare these, the difference is about 3% which would translate to about a 3% increase in speed and distance given the same RPM and gearing ratio turning the wheels at the same number of rotations per minute. To go 1 mile, the 17" rotates 875.6 times, the 18" 847.5 times, about 28 revolutions difference per mile. That may or may not really add up over time.

 

So as suggested above, having the smaller rims, but set up for the larger rims would indeed run your mileage up, i dont know if 3% would make a huge difference between these two or not in reality - are they even calibrated that well to start off with? That 36k miles reading might really only be 34,020 miles, the 60k warranty would expire at 58,200 miles. Cops are "supposed" to give you x% over the limit for faulty speedometers according to some folks, so i have my doubts as to how accurate those readings are anyway. I was wondering this the other day, but i assume when they manufacture the Edge that they set the speedometer and odometer for the rim size that was on the original order option form - i.e. 17 or 18" and there is a slight difference in these.

[Mattsgt]

No sidesteps/bars yet, we asked and nothing out there so far. However we were told that people who create the aftermarket equipment such as the steps might well have bought an Edge to start taking it apart to fit in their products. Nothing from Ford for sure yet though.

 

As for the math, really its just the difference of 1" in diameter in the rim and a slightly different tire - which is just under 1" in height on the vehicle overall. However there could be just as much spring contraction based upon the weight of and in the vehicle and its distribution. Looking at the rims and tires, assuming no compression of the wheel walls the 18" rim is 1" larger than the 17", the tires are P235/65 R17 and P245/60 R18, which when added to the rim would result in 0.77" difference in overall diameter of the rim and tire due to the lower aspect ratio and wider width of the 18" tire. When you calculate out the circumference of each of the tires the 17" gives 6.03', the 18" is equal to 6.23', difference of 0.2' (~2.5"). When you compare these, the difference is about 3% which would translate to about a 3% increase in speed and distance given the same RPM and gearing ratio turning the wheels at the same number of rotations per minute. To go 1 mile, the 17" rotates 875.6 times, the 18" 847.5 times, about 28 revolutions difference per mile. That may or may not really add up over time.

 

So as suggested above, having the smaller rims, but set up for the larger rims would indeed run your mileage up, i dont know if 3% would make a huge difference between these two or not in reality - are they even calibrated that well to start off with? That 36k miles reading might really only be 34,020 miles, the 60k warranty would expire at 58,200 miles. Cops are "supposed" to give you x% over the limit for faulty speedometers according to some folks, so i have my doubts as to how accurate those readings are anyway. I was wondering this the other day, but i assume when they manufacture the Edge that they set the speedometer and odometer for the rim size that was on the original order option form - i.e. 17 or 18" and there is a slight difference in these.

 

You have a lot of time on your hands don't you sim! J/K :yup:

[sim]

You have a lot of time on your hands don't you sim! J/K :yup:

Sometimes

 

It only took 5 mins to find the info and then do the calc's.

[TJW]

Changing the diameter of the tire will throw the speedometer and odometer off. Specifically, going to a smaller wheel will cause the odometer to accrue miles faster, depreciating your vehicle faster and using up the warranty faster. So I wouldn't do it.

 

That said, there is probably very little difference between the two. Anyone care to do the math?

 

No math need be done.

The 17s have a higher profile tire than the 18s, so their outer diameters are almost identical.

[sjsutton]

Besides the additional bling factor, and unfortunately probably a higher replacement cost when they wear down, the slightly larger wheels usually offer a slightly smoother ride over bumps, that is one advantage to them.

 

 

How do larger wheels result in a smoother ride over bumps?

 

Larger wheels usually have tires with shorter/stiffer sidewalls; resulting in a harsher ride.

[sim]

No math need be done.

The 17s have a higher profile tire than the 18s, so their outer diameters are almost identical.

As noted above, the difference is about 3%, it makes a little difference over the life of the car, but in the grand scheme of things pretty similar.

How do larger wheels result in a smoother ride over bumps?

 

Larger wheels usually have tires with shorter/stiffer sidewalls; resulting in a harsher ride.

Assuming that the sidewalls arent shorter (which to be honest 60% of 245 vs 65% of 235, 6mm per wheel wall is not much again), the extra size would allow the tire to roll over a bump a little easier than a smaller tire which would kind of bump into it and kind of bump over it as it tried to roll past it - think of the size of the object versus the wheel size. You can notice the difference in 14 to 18" wheels say moving over a 1" high bump, the difference between 17 and 18" wheels might not be so pronounced.