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Still trying to work a deal on a 2018 Touring.

Is it really 1 second slower 0-60 with the 18" wheels than the 16"?

8.6 vs 9.6 seconds according to 0-60times website.
 

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Well, it should be slower as it weighs more, but those figures are suspect. The tires will hurt your mpg, but not that much compared to the couple hundred pound or so penalty over the FE trim.
 

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You planning on some red light races with the Niro or something aha? Larger tires will definitely result in slower acceleration. You could always try to balance that out with aftermarket weight saving rims.
 

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Well, it should be slower as it weighs more, but those figures are suspect. The tires will hurt your mpg, but not that much compared to the couple hundred pound or so penalty over the FE trim.
Actually, the tires (and specifically their width) have a huge impact, moreso than the weight. Wider tires produce a lot more friction and drag. You'll notice the EX with the Premium package, which has the same weight and features as the Touring other than the tires (it uses the narrower ones from the LX) gets the same fuel economy as the LX rather than the Touring.
 

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Wider tires are more likely to have positive benefits in 0-60 times because of better grip (friction) on the road. That extra drag is unlikely to have a measurable effect on 0-60 (could even improve o-60 with the better tire grip), but as I did say, it will have an impact on mileage. The width of the tire is not the only drag (sorry) on the fuel efficiency. Lower profile 18" wheels by their very nature have less flexible sidewalls, and thus higher rolling resistance.

If you think tire size is more important than weight on a low powered car for 0-60, well, read a physics text chapter on acceleration. Think about accelerating up a hill. Steeper the hill, the more difficult to get up to speed, right? Think about a lighter car with the same power performing the same task. Put stupid wide tires on the lighter car. Which one will get to the top of hill first?
 

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I thought I read that they had the same outer tire diameter with the different rim sizes?
They do. But the larger the rim, the smaller the sidewall. The smaller the sidewall, the wider the tire, in order to increase the contact patch. The larger the contact patch, the more friction between the tire and the road, and more rolling resistance.

The width of the tire is not the only drag (sorry) on the fuel efficiency.
Based on the EPA rating, the width of the tire is in fact the only drag on fuel efficiency here. The Touring and the EX with the Premium package would have the exact same weight as the only difference in spec is the wheel and tire package. And a drastic difference in fuel economy, much more drastic than the MPG difference between the loaded EX and the lightweight FE trim.
 

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The width of the tire is only one factor at work here. Another one as I stated is the tire profile. Last one is that this tire was not designed for efficiency in the way that it was constructed, belts and materials used versus the Michelin OEM for 16" wheels.

You have an odd idea of how profile affects tire width. It is independent of width and multiple profiles are available for the same width for cars. Ever look at truck tires? They are certainly not low profile. What about earth moving tires? Some of those are as wide as entire cars, and extreme high profile.
 

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I guess I don't care about 0-60 on a Hybrid. I just took a 2018 Touring on lease and its seems to have plenty of punch for me ...ie. the battery/torque kick of a Hybrid. If I want real 0-60 punch I'll get in my Mini Cooper JCW GP Supercharged pocket rocket. However I find the 18" Michellin treaded wheels very smooth riding. I was not expecting that and I love it. It may have to do with the Niro having a slightly stretched wheelbase compared to others in its class but I was impressed on my test drive as was my wife and we continue to feel that way. The combo of that wheel/tire package and I think very well designed suspension is a winner.
 

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The width of the tire is only one factor at work here. Another one as I stated is the tire profile. Last one is that this tire was not designed for efficiency in the way that it was constructed, belts and materials used versus the Michelin OEM for 16" wheels.

You have an odd idea of how profile affects tire width. It is independent of width and multiple profiles are available for the same width for cars. Ever look at truck tires? They are certainly not low profile. What about earth moving tires? Some of those are as wide as entire cars, and extreme high profile.
The lower the tire profile on a car, the wider you make the tires. This is to compensate for less compression available on a narrower sidewall that would otherwise widen the contact patch just from the car sitting on the tires. You may know physics in general, but you have a few things to learn about their practical application in the automotive space.

So when you take a Niro, which normally comes with a 16 inch rim and associated tires, and then you replace those with 18 inch rims with lower profile tires, those lower profile tires will be significantly wider than the 16 inch setup. Among many other differences in ride and handling, the wider, lower profile tires with the extra rubber contact area create more friction with the road, requiring more power to roll.
 

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The formula for friction does not include a "width" so the fact that the tires are wider really doesnt matter. What matters is construction and mass in motion. In the calculation for rotation, the weight is a squared function. 2 pounds = 4 felt pounds, 3 pounds = 9 felt pounds etc.
The width probably add some air resistance.
 
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