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175/70r12's on Stock Rims?
Topic Started: Mar 5 2012, 02:11 PM (1,795 Views)
Woodie
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clarkdw
Mar 8 2012, 12:24 AM
Woodie
Mar 6 2012, 06:43 AM
Those were the baddest tires available 10 years ago

We used to use these on the autox cars in the late 80's early 90's.
:smackface

Okay, so I'm old and time is dilating. Doesn't make me a bad person, does it?

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clarkdw


Woodie
Mar 8 2012, 06:47 AM
clarkdw
Mar 8 2012, 12:24 AM
Woodie
Mar 6 2012, 06:43 AM
Those were the baddest tires available 10 years ago

We used to use these on the autox cars in the late 80's early 90's.
:smackface

Okay, so I'm old and time is dilating. Doesn't make me a bad person, does it?

They may well still have been the baddest tires when you youngsters were playing a mere decade ago.

I just know about the time back when I was racing and autoxing. That would be when the tires were chipped out of solid granite. :D
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clarkdw
Mar 8 2012, 09:54 AM
They may well still have been the baddest tires when you youngsters were playing a mere decade ago.

I just know about the time back when I was racing and autoxing. That would be when the tires were chipped out of solid granite.
Does this mean modern stickies are even stickier? but do they go away quicker too.

I saw some Yokohama A0somethings that were basically slicks. wow.

Tom
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clarkdw


Street tire technology took an enormous leap in the late eighties with the introduction of A008 type tires that were simply race tires with DOT approval. Since then the compounds and use of multiple compounds in a tire has brought us to the point that using what is considered a high performance street tire today will give faster times on a road course than full on qualifying slicks of 25 years ago on the same vehicle. Tire life has changed for the better as well but the obvious is still true. The stickier the tire, the shorter the life, race tires are no good for the street and don't expect snow tires to live long in the summer.
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An update...

I've run tires with too narrow rims and am acutely aware of how rim width contributes to steering response. In fact, increasing rim width with the same tire is usually a marked improvement.

So I have these (8) A-008's which have a recommended rim width of 5-6" which makes the stock 12x4's really narrow...

What to do...

Well, I'm pretty sure, one way or another, I'm going to weld up a set of 12x6 rims. Might choose 5.5 or even 5 to make them more friendly to stock tire sizes (what is the max recommended rim width for the stock 80 series 12's?)

Since the increase will only be of the order of an inch, I think I can eliminate the "ring" typically used to widen the rims. I can use (2) wheels to make (1). And that will require a simple butt weld.

I talked with a local machine shop that does driveshaft welding and they do it, but only not in summer because they get so busy. The fellow I was talking to, when I told him I'd do it myself if I could swing the rims on my lathe and also had the welding equipment/skill etc., said when he was young he would cut rims on the car! Put a jack stand 1/4" from the rim, run the engine to turn it, then weld a cutoff tool onto a 4' pipe and cut them off like you were turning wood!

Talk about Lo-Tech! I love it!

But I may modify the method and use an abrasive cutoff wheel on a 4.5" grinder. Make a fixture to hold the grinder and get to it.

The only downside to this is that the offset error is 1/2 the width increase since the widening will be inboard. Because of that I may stick to only 5" since I'm sure it will be a lot more difficult to steer the car.

The other thing that I like about this approach is that raising a car with larger diameter wheels is a very bad thing to do when handling is concerned. Since the 165r65-13's are the same diameter as the stock 12's, even these 170R70's will be a +1 change in tire size. While bad, at least not as bad as a 170R70-13 which is +2.

I've already gotten a spare set of 12's and had a 2nd set almost in hand - but maybe will still get them in mid-May if they are still around. Then I'll have all the pieces.

I do have a friend who has a machine shop that has the machines and skill to do this job. I may ask him what he wants to do it.

I have to laugh. Looks like I'm going in the wrong direction(!)
Tom

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Scoobs
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:D

Why cant you just mount them on the rims as is? I dont see anything wrong with it.
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Oh I could mount them all right, but when you reduce rim width, the sidewall does not work properly on the tire and steering responsiveness is reduced. The great thing about a light car with good grip is that the instant you snap the wheel, the car can virtually explode sideways and with great precision.

With the heavier GEN3 sway bars on my GEN2 and the A-008's, there is a lot of potential in this combination and wider rims would add to the experience.

(If you look at a cross-section of a tire as it scrubs around a corner, you can see how proper sidewall position improves as rim width increases.)

I also found the Fiat 500 Abarth has -1.5deg camber on the front which is very aggressive. I'll probably do that too. The A-008s have an outer band that is wider than the other ones and is also a slick - so this tire will handle almost like it is a slick.
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clarkdw


Is it worth the trouble for the 5k miles that these tires will last? (optimistically)
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Well, that's where their "advanced age" comes in - the rubber has definitely gotten harder.

Then I would expect some extra life due to the Metro's 1700 lb fly weight. While not a Berkin or Caterham, those guys don't know what it means to ruin a set of tires at a trace day.

I'm still looking for some Fiesta alloys. They are 12x4.5 which is only 0.5" out of min spec. If I was 6" instead of a 7" min, that would be one thing, but 4 out of 5 is, percent wise, a pretty big difference.
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Scoobs, maybe I should mount them and just see what they are like. I know that would be sensible, but sensible sometimes doesn't fly here(!)

You give good advice!
Tom
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Finally, today got the 008's mounted on Festiva 4.5" mags and the handling is really impressive.

I also think the 4.5" Festiva mags (or steels) are a must. The OE 4" are just too narrow. Even with garbage tires, that extra 0.5" makes a dramatic improvement.

I'm "taking it easy" and checking the tires since they were so old and have found myself going around corners faster than ever - and this is without trying at all. Its just they're that sweet to drive.

My guess is that they will be a very nice combo but unfortunately, now unobtainable. I suppose there may be a few caches of 008's out there, but probably fewer undiscovered than lightweight Hemi cars.

Now that the "game is on," I really need to step up and do something with the springs and struts. I know everyone cuts a turn out of the fronts, but than changes the spring end from a "semi-square" to a pure tangential which puts a lot of bend and resulting side load on the strut bearing.

Also need to come up with some alignment specs for high performance driving.
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