Thank you for the good information. Since you took "responsibility", I'd
love also some advice . . .
I am looking to do suspension mods to increase handling performance. I
don't mind harsh rides, as long as I can turn the front wheels. I am not
concerned with Speedometer accuracy, just handling and performance.
Has anyone used some very low profile tires, say 35 to 50 series tires with
a 6" or 7" wheel. Opinions?
Anyone that has used 16" wheels? If so, What brand? Opinions?
Thanks,
Dave
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Original Text
>From <rgb@exact.com>, on 1/25/98 2:00 AM:
>I take no responsibility for accuracy.
Good point, I'll accept responsibility for mine. After seeing this
argued for years, and friend and myself (both drinking too much beer)
mentioned we had "some" mounted TR6 wheels with different tires...
Can you believe we had "five" different brands of almost new 185-15
tires mounted on stock TR6 rims? We managed to gather "five" different
brands of 205/70-15 among the larger collection.
The exact match in car ride height is the 205/70-15.
There are several points of interest:
1. The 185-15 tire was not a "series" tire, i.e. not marked,
I've seen this referred to as a "performance radial", hence
close to 78 ratio, not 80 ratio... My actual measurements
show the old redline as a 79 ratio, it was the largest, the
other 185-15's including the G800 seemed to be about 78.5.
2. No one seems to take the profile into account. As the tire
becomes wider for a given load, the "patch" stays the same,
but rotates from narrow and long to wide and short (clear
as mud). This means that the squeeze in the diameter direction
is MUCH less as the tire gets wider on the appropriate rim.
Check out the new cars on 50 series tires, almost NOT visible
bulging at the bottom.
3. Wider tires are usually for performance reasons, they give
a harsher ride and more grip. It is harder to turn the steering
wheel. Any mis-alignment, etc. is more noticable. There is
a limit to how wide a tire on a given wheel will improve performace.
Most books and data I've seen limit a 5.5" rim to 205 tires.
4. We started by placing all 5 185-15 mounted tires together and
placing a yardstick across the top then measuring the gap.
Ditto with the others. What is most interesting is the variation
in tires of the "same" size. Even the new 205/70-15 varied
3/8" in diameter between brands...
Opinion:
On a stock rim, a 215 or 225 will "bulge" and not keep the tread
as flat. If you've got 6" rims, a 215/65-15 is a nice size. I
run these on my 7" Panasports. If you run these wide rims, I'd
switch the outside ball joint bolt to 2.25" grade 8 (stock is 2.5")
and rebush the upper A-arm at a minium in Poly or Nylatron to prevent
the sloppy movement which allows these wheels to touch. Let's face it,
you need this even with stock wheels, especially on the rear. BPNW
has a $125 kit for the TR6, works great with stock springs for fast
street usage. I like the Nylatron rear kit best as it fits nicely.
In any case, pack all this with synthetic lube to keep the water out
and prevent squeaking.
Also, check the rear hub studs, the wider tires will pull the
rear off the car if half this stuff is stripped, broken, etc.
Use a torque wrench on those nylocs. The ones that move each
time you hit them with the same setting are stripped - FIX'EM.
If I was going to spend money on Panasports, I'd buy the 15x7 rims.
These are 1.5" wider than stock and serve to stabilize the 215 tire
tread. These are zero offset, so give you 1/2" more track as well.
TRF has these buried in the price list only, see the "FSxxxx" section.
TRF's come with hubs, bolts, etc. ready to go... With the Winter
parts sale, buy 3, get one free! These get rid of the bent steel
wheel vibration at the same time.
WARNING: your suspension better be in good shape, your fenders
etc. better be straight, these fill the wheel wells and if
you've got a smashed fender or bent frame or other major
mechanical suspension problem, fix it first.
I really like the new Michelin 205VR70-15 tires on stock rims. These
are difficult to find, NTB special order at $100 apiece. For the
7" rims, Michelin has a new "Pilot" performance tire available in
only one 15" size, yep, 215VR65-15... this is nice. One tire out
of each set required "NO" weight, all the rest required little.
(the Michelin's cost more, but each place I've visited over 20 years
always says the same thing... easy to balance, always round)
All the other brands I've tried needed loads of weights.
For cheap, the Goodrich 205/70-15 are about $45 apiece. These
hold well, but have soft sidewalls, so handling is anything but
crisp. Perfect for bent rims and weak suspension pieces, or
those that want a "touring" ride.
--
Roger G. Bolick, rgb@exact.com 512-794-9567, FAX 345-2879
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