My tank still has the original steel wheels. The diameter is 15"... but I
never measured the width, and I can't make much sense out of the tables in
the shop manual.
But I think they are either 6", or 6.5" wide.
I've been thinking about getting some stock aluminum wheels, since a friend
is going to sell some soon. I'm wondering if they are actually wider than
the ones I have now.
Also, I've been looking into some crager wheels, but the smallest width I've
seen is 7", for 15" wheels.
Would getting a wheel of 7" in width, or getting a 14" wheel, with 6" in
width cause horrible things to happen to my suspension and/or wheel berings?
I'd really like to get some better looking ones.... but not at thet price of
runining my suspension and other parts.
Also, any input on crager wheels would be appreciated :-D
As far as the obvious is concerned, all other points remaining the same,
a larger diameter wheel will raise the ride-height as measured to the
frame. In terms of the chassis' ride and cornering behavior, changing
the width and/or offset of a wheel and tire combo will impact the track
width and/or scrub radius. The scrub radius is the dimension, laterally
on the pavement, from the tire centerline to a line drawn through the
upper and lower balljoint pivot points. An increasing scrub radius, in
addition to somewhat impacting tire wear characteristics, will impart
increased resistance to driver input. Deflection in the suspension
bushings can be expected to increase as well. In
reality, if the car is just a daily driver that never sees any
competition-oriented driving, the effects can be somewhat negated by
specifying alignment angles closer to neutral. Camber in particular
should be adjusted. In short, expect any
scrub-radius-increasing change to increase steering effort. Widening
track width via offset changes will increase the leverage upon wheel
bearings, with a negative effect upon longevity. A wider tire/wheel
combo with an appropriate offset compensation to preserve existing track
will not typically impact wheel bearing loading, although it may to some
degree impact the chassis' behavior.
On Mon, 31 May 2004 19:22:08 -0600, Robotnik wrote:
Thanks for the info. If I changed wheel diameter, I would keep the tire
diameter the same. I figure if I went with a wheel of the same width, and a
diameter 1 inch smaller, but keeping the tire diameter the same, they might
just wear a little more quickly.
Am I anywhere near correct in this assumption?
If the total diameter of the wheel/tire combo, the contact patch width,
and the offset (dimension of the mounting flange versus wheel centerline)
all remain the same, tire wear characteristics would mostly remain
unchanged. If the wheel diameter is decreased and the aspect ratio of
the tire (sidewall dimension) is increased a corresponding amount, the
increased sidewall may smooth the ride somewhat. On the flip side of the
coin, a taller wheel and shorter aspect ratio may make the ride rougher.
With the tire absorbing less of the road surface changes and instead
feeding them into the suspension (the rough ride), the suspension may be
compromised in its ability to keep the tire properly in contact with the
road as the suspension cycles. This would have a negative impact upon
tire wear, but it is not likely to be very noticeable.
On Tue, 01 Jun 2004 09:14:01 -0600, Robotnik wrote:
So, of all the cases we've discussed here... it looks like if I do change
anything, the best (other than an identically measuring wheel) would
probalby be to get 14" diameter wheels, with the width equal to the
original, offset equal to the original, OD of the tire the same as original,
and contact patch width (I'm not a tire expert... is this the width of the
part that is in contact with the road?) the same as the original.
And in doing that, I might benifit from a slightly smoother ride.
Thanks alot marky, you've been very helpful.
A very valid concern regarding brake parts. And then there's the fact that some
may find a 14" wheel to be somewhat odd-looking on such a large car.
All this is not to say that increasing the offset a half inch positive
and increasing the total wheel/tire diameter an inch is going to make
your vehicle a hard-to-drive maintanance nightmare, but from an
engineering standpoint, yep, it's pretty hard to change anything from
stock dimensions without some degree of degradation. On a non-handling
related point, I should mention that a change of the total diameter of
the wheel/tire on the rear of the car will render the speedo/odo
progressively inaccurate. And contact patch is the 'footprint' of the
tire on the road.
On Wed, 02 Jun 2004 13:07:56 -0600, Robotnik wrote:
Yeah, I knew that changing the total diameter will cause accuracy issues
with those gauges. That's probably about the first thing I thought of
actually, since I knew I didn't want to have to change any gears out for
them. I've looked at a few styles of wheels, I think that even with an inch
smaller diameter than the original wheels, they would still look pretty
good. I think they would look worse to INCREASE the wheel size. But, I'll
ahve to get under and look/measure and make sure the brake parts will clear.
I'm sure the rotors/drums will, but I"m not sure about the calipers on the
Thanks, once again.
With tyres and rims, there is a equation that dosnt change the running
diameter of your rims. like 205/65 x 15 should go down to 215/60 x 14 and
225 /55 13 thus keeping teh outside diameter of the tyres to that of a 13
inch rim. It also allows the stock brakes to be used, as the inward dish of
the rim is of normal distance and dosnt put the speedo out at all..
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