Will going from 17" to Limited 20" wheels affect my speedometer or ride?

I just purchased a 2016 4runner SR5.
Will it change anything if I want to go from the original ugly 17" wheels to the Limited 20" wheels. A "adviser" at the dealer said it would change the speedometer and ride stiffer. I'm new to the 4runner world so go easy lol.
Thanks in advance for any help.

 

The dealership adviser is an idiot. The overall diameter of the SR5 wheels/tires and Limited wheels/tires are identical at 31.6" so your speedometer will remain completely unchanged. Ride stiffness will be a negligible change as well as you're only loosing 1.5" of sidewall. Ride harshness regarding tires will be far more influenced by tire compound/construction than an inch and a half of rubber.

Also, welcome! Don't let any of the above make you think I'm being hard on you at all.

 

Thanks for your reply. I didn't think the wheel size changed the tire size. This said adviser also informed me (don't laugh too hard), it's designed to pull slightly to the right, which it does. The pulling is why I took it back to be checked. It has 3,500 miles on it. The front tires have a little wear which in my humble opinion should not happen. That's where I've decided to take it to another dealer since it is under warranty. I think they just didn't want to align it.

 

Most properly built roads have a "crown" or a downward slop towards the shoulder like shown below.



It's not always as aggressive of a slope as shown above but it can create the sensation of pulling to the right since in America we drive on the right side of the road. You'll notice this sensation of pulling from road crown a lot more in SUVs/trucks as tire wander is more pronounced than in a car. A good way to test to see if its the road or your vehicle is to drive on the left side of the road, ideally a side street where there's no on coming traffic.

 

I understand the road crown however with little over 3,000 miles on a new vehicle the tires shouldn't be wearing as aggressively as mine seem to. I drive full size trucks and my son has an older 4runner and they don't pull like this 2016 does. Also I have one more question if I may, i have the standard power mirrors. Can I upgrade to the ones with turn/puddle lights just plug and play? Are the harness plugs the same? Thanks guys.