Replacing 17" Stock Wheels With 16" Stock - Any Negative Effect?

My '03 Toyota Matrix XR has 17" stock wheels, which apparently came with its
"Sports Package" (I bought the car slightly used from someone). I want to
replace the wheels with 16" stock wheels, which is the original wheel size,
because I want tires that are supposed to be especially quiet that come only
in 16" size. Someone told me that changing the wheel size might cause
mechanical problems for the car because the transmission was somehow
calibrated for the Sports Package. Is that true? I've heard that the
speedometer will be very slightly affected, but will there be other issues?
Does it affect the manufacturer's warranty?

Thanks.

"john" > wrote in message
...
> My '03 Toyota Matrix XR has 17" stock wheels, which apparently came with
its
> "Sports Package" (I bought the car slightly used from someone). I want to
> replace the wheels with 16" stock wheels, which is the original wheel
size,
> because I want tires that are supposed to be especially quiet that come
only
> in 16" size. Someone told me that changing the wheel size might cause
> mechanical problems for the car because the transmission was somehow
> calibrated for the Sports Package. Is that true? I've heard that the
> speedometer will be very slightly affected, but will there be other
issues?
> Does it affect the manufacturer's warranty?
>
> Thanks.
>
>
>

Hmmmm....didn't we cover this already?

"john" > wrote in message ...
> My '03 Toyota Matrix XR has 17" stock wheels, which apparently came with its
> "Sports Package"

The biggest thing to be careful of is will the 16" wheels fit? If the "sports package"
came with bigger brakes (or if the previous owner installed them) the larger wheels
may be required.

When thinking about speedometer calibration issues, don't look at rim diameter
(16" vs 17"), look at the actual size of the tires. Compare radius, diameter, or
circumfrence, but be clear about what you're doing.
Tire radius = (wheel diameter/2) + tire width*(aspect ratio).

Of course you will need to convert to the same units--our wheels are measured in
inches, and the tire width is measured in mm.

Here's an example, a 225/50-17 ti
(17"/2)(25.4mm/1") + 225mm(.5) = 328mm tire radius.

Also speedometers typically read a little too fast. It's common to have a speedometer
read 67 or 68 when you're going 65. If you check yours before changing the tires,
and consider how much larger or smaller the radius of the new tires is you'll know
exactly how the tire size change will affect the speedometer reading.

Well, there is truth to that, and a little deception.

If you went from a 215/45x17 to a 215/60x16, then the diameter would go from
about 12.5" to about 12.35", the difference being about 0.15" (less than
one-quarter inch in diameter). A difference this small would be negligable.

I calculated these sizes using my calculator at my desk, but there are Tire
Size Calculators on the 'net that will tell you exactly what the affect of
changing from 17 to 16 inch tires will be.

Honestly, I don't think you will get the desired results from your course of
action. That is, I suggest you car creates noises that even the most quiet
of tires will not silence. I think your Matrix is noisey from the wind, and
that part of its economy pricing is the lack of sound deadening that went
into the engineering.




"john" > wrote in message
...
> My '03 Toyota Matrix XR has 17" stock wheels, which apparently came with
its
> "Sports Package" (I bought the car slightly used from someone). I want to
> replace the wheels with 16" stock wheels, which is the original wheel
size,
> because I want tires that are supposed to be especially quiet that come
only
> in 16" size. Someone told me that changing the wheel size might cause
> mechanical problems for the car because the transmission was somehow
> calibrated for the Sports Package. Is that true? I've heard that the
> speedometer will be very slightly affected, but will there be other
issues?
> Does it affect the manufacturer's warranty?
>
> Thanks.
>
>
>

> Hmmmm....didn't we cover this already?

We may have covered the effect on speedometer, but ... I was curious as to
whether there are effects on the transmission's health and/or whether it
affects Toyota warranty.

-John

Jeff Strickland wrote:
> Well, there is truth to that, and a little deception.
>
> If you went from a 215/45x17 to a 215/60x16, then the diameter would
go from
> about 12.5" to about 12.35", the difference being about 0.15" (less
than
> one-quarter inch in diameter). A difference this small would be
negligable.

Err.. a tire with a calculated diameter of 12.5" mounted on a 17"
diameter rim???

215/45-17 = diameter 24.8" = 840 revs per mile
215/60-16 = diameter 26.0" = 807 revs per mile
numbers supplied from tirerack.com

Jim

> wrote in message
oups.com...
>
> Jeff Strickland wrote:
> > Well, there is truth to that, and a little deception.
> >
> > If you went from a 215/45x17 to a 215/60x16, then the diameter would
> go from
> > about 12.5" to about 12.35", the difference being about 0.15" (less
> than
> > one-quarter inch in diameter). A difference this small would be
> negligable.
>
> Err.. a tire with a calculated diameter of 12.5" mounted on a 17"
> diameter rim???
>

Opps, that's radius. Sorry.

215/45x17
The rim has an 8.5" radius plus the sidewall of 3.92, therefore radius +
sidewall = 12.42, the diameter is 24.84

215/50x16
The rim has an 8" radius plus a sidewall of 4.35, therefore radius +
sidewall = 12.35, the diameter is 24.70


Radius is half the diameter of the rim.
Sidewall is calcualted by multiplying the cross section (215 in our example)
by the aspect ratio (45 or 50 in our examples), then adding the results.
This will not be perfect, but if always done the same way, then any error on
one tire will exist on any other tire, and the relative difference between
the tires should remain about the same.



> 215/45-17 = diameter 24.8" = 840 revs per mile
> 215/60-16 = diameter 26.0" = 807 revs per mile
> numbers supplied from tirerack.com
>
> Jim
>

I think the equivelent to the 215/45x17 is a 215/50x16. By my math, I get a
12.42 radius, or 24.84 diameter for the 215/45x17, and I get a 12.35 radius,
or 24.70 diameter with the 215/50x16. These two tire sizes are functional
equivelents. The difference in diameter is just over 1/10th of an inch,
which works out to about 2.5 millimeters on the diameter.

In any case, my math could be in error. The point is, if one knows the size
of a tire, then one can use a calculator to determine the equivelent tire
that fits a smaller or larger rim. I pulled some numbers out of my ass to
illustrate the point, going to tirerack.com and using the calculator clearly
is a better choice when one needs greater precision.

On Tue, 1 Feb 2005 15:09:05 -0800, "john"
> wrote:

>> Hmmmm....didn't we cover this already?
>
>We may have covered the effect on speedometer, but ... I was curious as to
>whether there are effects on the transmission's health and/or whether it
>affects Toyota warranty.
>
>-John
>
You don't have to worry. You won't notice any additional wear or
damage to the transmission. The warranty won't be affected either.

On Tue, 01 Feb 2005 15:09:05 -0800, john wrote:

>> Hmmmm....didn't we cover this already?
>
> We may have covered the effect on speedometer, but ... I was curious as to
> whether there are effects on the transmission's health and/or whether it
> affects Toyota warranty.
>
> -John

Oh! OK!
In that case, no! Just make sure the tires are all the same size. But that
should be obvious anyway. you can mix sizes on the same axle, unless it's
4WD or worse, AWD. But as long as they are all the same size, the tranny,
etc don't care.