I read some where on this site that if you get the 19 inch rim that it will throw off the navi. With the 19’s the circumference of the rim is bigger than stock and the navi is calculating with a smaller rim size.

So has anyone noticed anything wacky with their navi or anything else for that matter after putting on the 19’s

 

Generally, they will go with reduced sidewall heights in Plus 2 fitments - that is standard procedure. Of course, it will take longer to get where you are goping, since acceleration and braking are adversely affected.

 

navi is satilliete linked, better known as GPS. you could technically run it on monster truck tires and it should give a fairly accurate location

 

Cool I was just wondering. Thanks for the info guys.

 

Are you saying this under the assumption that the 19s would be heavier than the oem 17s or 18s? If not, I'm curious as to what the reasoning is. Thanks.

 

Not heaver but bigger in the size of the rim. I am not to sure how it works. But with 19 inch rim it will take X amount of inches for it to make one revolution compared to a 17 inch rim. I think that’s where things get screwed up.

Can some one please explain how this works? I would like to know the full details too.

 

yes and no, the navi runs on gps to get position but also relies on wheel speed to estimate speed and distance traveled of the vehicle. for instance if you do not have a signal when driving through a tunnel it will use the vehicle speed to guess how far you have traveled.

 

there is a menu in the NAVI diagnostic that lets you set this (apparently), but nobody has really documented it and reported back on what it does. you can get to it by pressing and holding MENU, MAP, and CANCEL.

 

if the circumference of the wheel(with tire) is larger than the stock circumference(with tire) then with every revolution of the 19 inch wheel it will have traveled a little further than what the car thinks its traveled. so for instance if the stock circumference was 60 inches and the 19 inch is 65 inches, each revolution creates a 5 inch difference in distance traveled. this coupled over the course of a long distance can lead to error in the actual distance traveled.

 

Zeezz lets get to searching. We don't have all day damn it. Well we really do have all day and the rest of the week if we want. But hell we all want to know now. Find that answer


caball88 couldn't have said it better myself. Actually I couldn’t have said it all because I had no idea what hell I was talking about.

 

Ah, metal is heavier than rubber, right? Even if you keep the ratios correct you are STILL placing a heavier weight further away from the center of the wheel. Also, 99.9% of all 19" wheels are significantly heavier than 17" wheels. ==== Poor performance...

 

It has to do with weight perhaps - that would depend on the wheel design and tire. The real issue is that the moment of inertia is raised around the polar center. Simple physics.

For those who slept during class Imagine you have a giant carousel wheel, perhaps 40 feet in diameter. It would take significant force to move it, and to acclerate it to a given speed. Now take one 4 feet in diameter - child's play. Same principle here.

Oversize wheels also affect handling, as the suspension is optimized for the contact patch and physical dimensions of the stock wheel. That is one reason that tests of "tuner" cars often show worse skidpad, worse slalom, and worse braking. The braking is mostly the reverse effect of the acceleration drop - the higher moment of inertia of the wheel makes it want to stay in motion, per Newtonian physics.

19's are for looks - not for performance - very few tuners have the engineering skills nor the equipment needed to get oversize wheels and tires right.

 

Donte, size of the wheel might put your car calculations off on no. of miles travelled or speed in mph but it will not affect your Navi. The distance travelled for Nav to plot depends on your current position, at a time, plotted on topographical map. For example, say NAv is calibrated close to 35 ft. , and you drive your car anywhere in this 35ft. circl, you are stationary. So going from 17-19" will not affect your Nav plotting.

BTW, 6MT is better than 5AT

 

Thanks everyone for the info. I eneded up getting the 19's and they will be in tomorrow. This is the rim I got.



JoganJani my pictures already proved that 5at is better

 

I like the lip on those rims, make sure to post pics!

 

That was the long version. The short version is this:
Rotational inertia increases with a larger sized wheel. Greater rotational inertia is bad because it means that it requires more energy to get it moving, and once moving, it takes more energy to slow it down from the momentum it has built up.

 

Do you have a science museum near you? If so, they probably have this on exhibit. When I was in Munich, I went to the Deutsch Museum. They had an exhibit with a hand-crank connected to a wheel. One had the weights close to the axle. The other had the weights about 5 inches away from the axle. Both apperatus weighed the exact same, but it was literally orders of magnitude more difficult to turn/stop the larger wheel.

 

put me in the .01%

My 19 x 8.5 's are 42 lbs with tires

-Chad

 

Donte99TL - While your Navi should work without any modifications (It is based off of GPS positioning, which your new wheels won't affect much), you should consider this: Your odometer may have a tendancy to read lower now.

It will work like this: Your odometer will probably be reading a sensor mounted to your front or read axle that will count a pulse each time your wheel goes through a full rotation.

All else being equal, if your wheel goes from 18" to 19", your circumference has changed from 56.5" to 59.7". Without tires entering in the equation, your sensor will "blip" once every 56.5" that you travel on the 18" wheels, and once every 59.7" inches for your 19" wheels.

End result: When you travel 100.0 miles, your odometer will read approximately 94.7 miles.

Before you get all excited, remember that I said "All else being equal" above. If you went with a lower tire height than stock, it will reduce the effects of your wheel change. If your new tires are 1" shorter, it will completely offset the odometer change due to the increased wheel size.

Cheers!

 

Rim size won't throw off the Navi. It does calculations by GPS, actual road speed, and distance to destination. Wheel size has nothing to do w/ its math. I tested this w/ my Navi on my TL. I had the stock 17" w/ Potenza's and recented changed to 19" OZ Galileo III's w/ Nitto 555's. The Navi still comes up with the same number regardless of wheel size.