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The fact that GM actually chose tires of an appropriate width for once. Most of the time GM screws up by putting tires that aren't wide enough for the vehicle's performance. But this time, it looks like they got it right. Kudos, GM!:cheers
 

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Good point. The XLR and the CTS-V both come to mind regarding tires being too narrow for the model/power.

For comparison some time, take a look at the width of the tires on a BMW 3-series (even the 185-hp 325) and compare to other models that make similar power. BMW definitely uses a wider tire. I am not engineer, but I would assume that only can help with traction and handling... and surely looks better to boot.
 

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A meaty contact patch is great, I'm just afraid of oversized heavy wheels. This car won't come with enough power initially to not be affected by 30lb 18" anchors. Last thing I want is the car to gain a bad rep based on factory performance numbers. I can hear the nickname now "Pontiac Slow- stice"
 

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Darkhamr said:
A meaty contact patch is great, I'm just afraid of oversized heavy wheels. This car won't come with enough power initially to not be affected by 30lb 18" anchors. Last thing I want is the car to gain a bad rep based on factory performance numbers. I can hear the nickname now "Pontiac Slow- stice"
bah! having a rep as a slowbe is what makes beating ponycars and vettes fun! :D btw, there any names out there for the ole grand prix?
 

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Bizz said:
bah! having a rep as a slowbe is what makes beating ponycars and vettes fun! :D btw, there any names out there for the ole grand prix?
Probably not, because.....who cares? LOL J/K bro.:D
 

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The Problem with Wide

Wide tires are fine when it's nice and dry, but get into slop, or especially snow and ice, and the car is basically worthless. They become great big skies. My Vette once slid off a road with a normal crown while it was stopped! Water planing in heavy rain is another problem. They are also not very comfortable, as a rule.
There is also the problem when real wide, grippy tires encounter
pavement that isn't perfectly aligned - one side of the car wants to go one way and the other side another. Very discombobulating.
Small errors in front alignment also are magnified greatly. They also cost an awful lot. Actually, I can't think of a single reason why I would buy a car with wide tires, unless I could re-wheel
it to my tastes.
 

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Re: The Problem with Wide

theBike45 said:
Wide tires are fine when it's nice and dry, but get into slop, or especially snow and ice, and the car is basically worthless. They become great big skies. My Vette once slid off a road with a normal crown while it was stopped! Water planing in heavy rain is another problem. They are also not very comfortable, as a rule.
There is also the problem when real wide, grippy tires encounter
pavement that isn't perfectly aligned - one side of the car wants to go one way and the other side another. Very discombobulating.
Small errors in front alignment also are magnified greatly. They also cost an awful lot. Actually, I can't think of a single reason why I would buy a car with wide tires, unless I could re-wheel
it to my tastes.
Best thing I can say to this, DON'T buy a sports car! Lots of nice Ford Taurus' out there for you.
 

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Re: The Problem with Wide

theBike45 said:
I can't think of a single reason why I would buy a car with wide tires

Umm... Performance? Oversteer? Grip? Friction? Maybe.

Well those are some reasons I like them at least.

-Whit
 

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Wide tires are actually worse for getting the power to the ground. They distribute the weight of the car over more surface area, so there is less pressure per square inch. Wide tires are great for cornering and all forms of handling, but aren't for drag racing..but really, who drags on a regular basis? Personally, I love wide tires for their handling and ride quality, but i see their drwbacks as well.
 

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SupraScoobyDoo said:
Wide tires are actually worse for getting the power to the ground. They distribute the weight of the car over more surface area, so there is less pressure per square inch. Wide tires are great for cornering and all forms of handling, but aren't for drag racing..but really, who drags on a regular basis? Personally, I love wide tires for their handling and ride quality, but i see their drwbacks as well.
Um, right... That's why dragsters have such skinny tires in the back... :rolleyes

Sorry, but you don't have a clue what you're talking about.



here are some actual drawbacks of wide tires:
cost
poor wet/snowy traction
gas mileage
drag (affecting highway speeds mpg and top speed, but this one is a bit picky)
weight

For a sports car like this, wider tires are a better fit for the intended use.
 

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skeptic said:
Um, right... That's why dragsters have such skinny tires in the back...
arent front wheel drive dragsters the ones with skinny wheels in the back? as far as i remember rear wheel dragsters have some pretty big slicks on the back!?!
 

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Vita said:
arent front wheel drive dragsters the ones with skinny wheels in the back? as far as i remember rear wheel dragsters have some pretty big slicks on the back!?!
You must have missed the sarcasism denoted by the :rolleyes emoticon...

But you are correct. FWD dragsters have big tires in front skinny in the back, RWD are the opposite... Hence, wide tires are better for the drive tires for drag racing. Opposite of what SupraScoobyDoo was saying.
 

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I think what was misunderstood in that statement was that it's not the width of the tire that is of greatest importance for drag racing launches it's the sidewall flex. Low profile street tires have very little sidewall flex and immediately transmit all torque to the contact patch / road surface interface and overcome traction. Drag tires "give" and store some of that energy.
 

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SupraScoobyDoo said:
Wide tires are actually worse for getting the power to the ground. They distribute the weight of the car over more surface area, so there is less pressure per square inch. Wide tires are great for cornering and all forms of handling, but aren't for drag racing..but really, who drags on a regular basis? Personally, I love wide tires for their handling and ride quality, but i see their drwbacks as well.
yeah, that's almost as far from the truth as you can get, however it should be noted that more accelleration force can be gained in adding hight to a tire rather than width. Width does help, just the contact patch of a taller tire is better for accelleration:

patch of tire contacting road (front of vehicle ^)

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Good for accelerating



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Good for turning

i dont remember the exact reasons for this off hand. i just remember reading about it in Carrol Smith's Tune to Win...
 

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syth82 said:
i dont remember the exact reasons for this off hand. i just remember reading about it in Carrol Smith's Tune to Win...
The key in this statement is "off hand..." :smile

The real explanation has to do with %long slip, lateral slip, and contact patch. At Purdue and UM classes in tire tech and applications to vehicle dynamics, you can go theough the evolution of the brush model to the elemental brush model, the telescoping elemental brush model (with hysteresis), then wrap it with a belt, study tread and compound hysteresis, tire pressure footprint distribution and Gough's inflation model,...

and after a semester or two in tire technology, you find out that Smith's Tune to Win is a decent enough half-pager on the subject.

Within limits, of course. There is no way a 185 wide 80 series tire will out accelerate a 245 wide 45 series tire.
 

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syth82 said:
yeah, that's almost as far from the truth as you can get, however it should be noted that more accelleration force can be gained in adding hight to a tire rather than width. Width does help, just the contact patch of a taller tire is better for accelleration:
Got to be careful with this one, taller tires require more torque to turn and while they do increase traction they will often make the car slower overall. Just ask anyone who runs bigger tires (ie, 4x4 drivers with big tires), they make the vehicle accellerate slower. Once the car is up to 40 mph for example, most people don't have a problem with the tires breaking free, but from my own experience there is a definate slowdown when running taller tires. But if you have the torque then taller tires can get you a little better traction AND get you going a little faster before changing gears.


For the solstice I would guess the best tire size for the 1/4 is going to be about stock height on a lightweight 15" wheel and somewhat wider than stock. But I don't plan to set mine up for the 1/4. From the looks of it I doubt I will make any changes in the wheels/tires at all. It looks to be great for handling.
 

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solsticeman said:
The key in this statement is "off hand..." :smile

The real explanation has to do with %long slip, lateral slip, and contact patch. At Purdue and UM classes in tire tech and applications to vehicle dynamics, you can go theough the evolution of the brush model to the elemental brush model, the telescoping elemental brush model (with hysteresis), then wrap it with a belt, study tread and compound hysteresis, tire pressure footprint distribution and Gough's inflation model,...

and after a semester or two in tire technology, you find out that Smith's Tune to Win is a decent enough half-pager on the subject.

Within limits, of course. There is no way a 185 wide 80 series tire will out accelerate a 245 wide 45 series tire.

Um, ya. That's what I meant to say. :blush


:thumbs
 

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Be careful of where you place your money. With under 100 hp and long gears a 185x80x13 (313 mm radius) might wll be faster accellerating than a 245x45x18 (339 mm radius) and that does not even consider rotating inertia.

Further I have serveral time experienced gearing that made second gear starts faster than first, the flywheel inertia of the engine limited its ability to rev fast enough. Ever hear of a "granny" low ?

As in anything else just about every car has a "sweet spot" of tire size and contact patch that is right for that car particularly if you must have the same size on all four. More is almost as bad as less.

Of course it depends on what you are trying to do. If performing a gag what you are after is visual effect and not speed so you want to make the car look as if it is going very fast at a relatively slow speed. Nothing better for that than a very wide tire on a slick surface and a slightly undercranked camera.

The real expert will see that the car does not move properly (at really high speeds the suspension will "float" unless cement truck stiff) but the popcorn crowd will never notice.

Might mention that at GMI I developed some of the first six degrees of freedom models for lateral forces in excess of a gee and while it gave some interesting (and surprising) things to watch for, it was just a starting place and the real "unfair advantage" was often close to but not exactly where the computers or the textbooks said. Keep in mind that high school physics says you can never have a coefficient of friction greater than one. Right.

So watch out for absolute statements, they may come back to haunt you.
 
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