Marcos Maniacs

Hi Paul,
Some thoughts about tires.  Tires that are more than 3 (?) years 
old start to get hard an provide less traction and grip.  In 
addition, modern tires will, if left sitting with the weight of the 
car on them for long periods of time, will seperate internally.  I had 
this happen with the original tires that were on the Marcos.  The 
tires looked really good, no weathering, cracks or wear.  One of the 
tires "looked low" so I checked the inflation and found that it was 
inflated properly.  On the way home on the same day it "came apart" on 
the freeway.  British Car magazine had an excellent article on this 
problem awhile back. Tire diameter or rolling diameter always needs to 
be checked when purchasing tires.  For example, looking at the chart 
for Hoosier racing tires on the inside cover of the December's issue 
of Grassroots Motorsports Magazine I see the following.  P205/60ZR13 
has an O.D. of 22.7 inches.  Compare that to a P205/55ZR14 at 22.8.  A 
mere .1 inches difference between a 13 inch wheel and a 14 inch wheel 
with the same brand of tire.  The 14 inch tire has a lower cross 
sectional ratio ie 55 for the 14 inch tire and 60 for the 13 inch tire 
but the point is still valid.  So choose your tire and wheel 
combinations carefully.  You can, of course go to the extremes with 
aP225/50 ZR13 at 21.8 and compare it to a P225/50ZR14 at 22.7 for a 
difference of .9 inches. So there are a variety of factors to consider 
including tire size, weight, grip, wear index, rolling diameter, and 
intended use.  With wheels the choices include strength, weight, 
width,and diameter and how they match up to the tires you are 
considering.  Lots of variablies and nothing is "clear cut" and many 
choices can be reasonable depending on the intended purpose. My 
choices are not necessarily "the best choice" for everyone else.  In 
fact, many of the decisions I made were based on factors that other 
would consider unwise... like a tire that only last for 10,000 miles.

Mike Denman
1966 Marcos 1800
Chassis # 4079 --- In MarcosManiacs@y..., pauldransfield@i... wrote:
> Mike,
> 
> You've provided an interesting paper on the various options open to 
you
> regarding the rims you wish to install on your car. But what about 
the tire
> size? 
> 
> I've had the same set of Michelin 70 series tires on my 13 inch 
Cosmic rims
> for the last 20 years.  This summer I noticed that my front right 
tire was
> badly worn on the inside due to an obviously misaligned toe-in 
adjustment,
> so I needed a new one. I've been thinking about changing to 14 inch 
rims but
> wasn't prepared to commit just yet, so I moved one of the rear 
wheels to the
> front and got a pair of 80 series tires for the back in the interim. 
These
> new tires have a greater diameter than the Michelins (they're the 
same size
> as the original Avons) but the difference in handling is very 
distinctly
> worse. On the other hand, the Michelins have never looked right 
because the
> smaller size doesn't fill the wheel well sufficiently (and the 
speedometer
> over-reads) but the handling has been superb. 
> 
> After speaking with a number of people about my dilemma, I'm leaning 
towards
> 14 inch rims with 60 profile tires. I want to go back to the 
original
> diameter because it looks better, it gives me more ground clearance 
and I
> think the lower profile will provide better handling. Unfortunately 
I'm
> undecided because I'm worried that this new combination wouldn't 
provide the
> sort of handling I'm used to. If it doesn't work out, it would be a 
costly
> experiment.
> 
> What are your thoughts (or anyone else's for that matter)?
> 
> Regards,
> 
> Paul Dransfield
> 3 litre Volvo
> 
> -----Original Message-----
> From: marcos18001966 [mailto:marcos18001966@y...]
> Sent: Monday, December 17, 2001 1:35 PM
> To: MarcosManiacs@y...
> Subject: [MarcosManiacs] Re: The saga has ended!
> 
> 
> Hi Don and Marcos Maniacs,
> I have been thinking about switching to Panasports for a couple of 
> years.  A conversation I had with Dave Methley in England confirmed 
> my thought process. (Dave races a 1800 like mine in England and has 
> won the championship 4 times) The decision went something like this.  
> The car presently has two bolt patterns on the wheels.  The cars has 
4 
> 1/4 inch  pattern on the rear wheels and 3 3/4 inch pattern on the 
> front wheels.  The wire wheel adapters got around this problem (and 
> the spare wheel problem).  I wasn't real happy with the smaller 
studs 
> in the front (3/8) as they are known to break occassionally under 
> stress.  The other parts of the problem are that wire wheels are 
heavy 
> (especially with knockoff adapters) and not as strong as their steel 
> or aluminum counterparts.(But they do look GREAT!) In addition, the 
> center sections of my wire wheels were showing signs of rust do to 
> poor plating.  The original owner noted the problem of poor plating 
> back in 1983 when he bought the wheels.  The spokes (stainless 
steel) 
> and the rims look great. I was talking to Dave Methley and he said 
> that part of my handling problem was do to the larger diameter 
> wheels in the back ( I can't keep the rear end glued to the road 
when 
> using a lot of power.  I can throttle steer like crazy,however 
;)Dave 
> said that the 1800's with a driver aboard has a  basically a 50/50 
> weight distribution.  The 14 inch wheels in the back put more weight 
> on the front and less on the back which contributed to my 
problem.(For 
> you guys with a "nose in the air" problem, the 14 inch rear and 13 
> inch fronts might work better... who knows?) If I went to 14 inch 
wire 
> wheels in the front I would have more unsprung weight (bad) and a 
> higher center of gravity (bad) and more ground clearance (good). If 
I 
> went with 13 inch wheels all around, then the reverse is true.  So I 
> decided to go with the 13 inch wheels.  It cost less to convert to 
ALL 
> new Panasports than to buy ALL new Chrome wire wheels (To get rid of 
> the rust problem) although price wasn't the issue. So with the 13 
inch 
> wheels I should get better weight distribution (by replacing the 14 
> inch wheels in the back only)less unsprung weight, and a lower 
center 
> of gravity.  The only negative is less ground clearance (1/2 inch 
due 
> to the wheel/tire change) which hasn't been as much of an issue for 
me 
> as for other Marcos drivers.  The Panasport wheels that I am buying 
> are 13 X 7 with a 4 1/4 backspace and 4 14 bolt pattern. I am also 
> changing to aluminum front hubs (lighter for less unsprung weight 
and 
> the same bigger studs as the rear wheels (7/16) and in the same 
> pattern). I am also changing the spring rates on both the front and 
> the back on Daves recommendation. The fronts springs are going from 
> 200 lb to 225 lb and the rears are going to 160 lb. The anti-sway 
bar 
> will remain the same at 7/8 inches. I am also going to new tires 
with 
> a really soft racing compound.  I drive the car less than 5000 miles 
a 
> year and the Yokohama AVS will last a hundred years at their current 
> rate of wear.  So rather than wait for the tires to get old, cracked 
> and hard, I decided to go with a racing tire (DOT legal) that will 
> wear out in less than 10,000 miles which will equate to two years of 
> use for me.  These tires are "super grippy" but with a high wear 
> component.
> I haven't decided what I am going to do with the wire wheels and 
> tires.
> Best regards,
> Mike Denman
> 1966 Marcos 1800
> Chassis # 4079
> 
> 
> 
> --- In MarcosManiacs@y..., "mcaqmd" <donlattimer@p...> wrote:
> > Mike,
> > 
> > Car looks great!  Why the switch to Panasports??  Are you going 
with 
> > 13" or 14" or are you keeping the 13" on the front and 14" on the 
> > rear?  
> > 
> > What are you going to do with the wires??
> > 
> > Don Lattimer
> > #3M5759 V6
> 
> 
> 
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