OK here is my idea, I want to put a good summer performance tire on front and rear, I want wider tires on the back, say a 275/40/18 and the stock 245/45/18 on the front. Any sugestions on brand. I don't care how they are rated Bridgestone is not an option for me, bad experiance in the past, but Michelin or Perelli or Goodyear would be great or Yokohama or Nitto.
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OK here is my idea, I want to put a good summer performance tire on front and rear, I want wider tires on the back, say a 275/40/18 and the stock 245/45/18 on the front. Any sugestions on brand. I don't care how they are rated Bridgestone is not an option for me, bad experiance in the past, but Michelin or Perelli or Goodyear would be great or Yokohama or Nitto.
i just dont trust them after all the things happened with their suv tires and some of the other tires. when they did the recall on those tires you start to wonder about the other tires they produce for cars performance wise
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If you can look past your bias against Bridgestone the RE050A Pole Position is fantastic and runs $186F/$236R
They are a great tire, and a great deal. If you can't get past whatever you're holding against them, you're the one who'll be worse off for it.
Personally I would not put wider tires on the back. Wider tires would give you less traction than the stock size. The rear end of this car is light to begin with, and if you have the LSD, you'll have to be really careful accelerating around turns.
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Actually, if the tire compound is the same, the traction friction would be the same on dry pavement. You have the same weight distributed over a larger area, so the area is larger, but the pressure per unit of area is lower, so it's a wash. On wet pavement or snow you would have less traction.
The main reason for using wider tires to get better traction in race cars is that it allows you to use softer rubber. A soft tire wears longer if it's wider, and it also has more sidewall strength, so the wider tires you see on race cars are just making up for the soft compound. If you're going to use street tires with the same compound, only wider on the back, you're just going to be spending more money for the same amount of traction, although they will wear longer.
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Austin:
Your theory has a lot of holes, new sporting tires grab better then tires of the past. The compound and the tread provide traction almost relative to the contact patch.
Just for the fun of it, see how much traction you have with a two inch wide tire on your car. Also petition the SCCA and NHRA so they stop penalizing cars for wider tires. By the way none of us are racing in the snow, but, you were correct with that point.
Austin:
Your theory has a lot of holes, new sporting tires grab better then tires of the past. The compound and the tread provide traction almost relative to the contact patch.
Just for the fun of it, see how much traction you have with a two inch wide tire on your car. Also petition the SCCA and NHRA so they stop penalizing cars for wider tires. By the way none of us are racing in the snow, but, you were correct with that point.
It's your money.
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Quote:
Originally Posted by AustinTashis
Actually, if the tire compound is the same, the traction friction would be the same on dry pavement. You have the same weight distributed over a larger area, so the area is larger, but the pressure per unit of area is lower, so it's a wash. On wet pavement or snow you would have less traction.
The main reason for using wider tires to get better traction in race cars is that it allows you to use softer rubber. A soft tire wears longer if it's wider, and it also has more sidewall strength, so the wider tires you see on race cars are just making up for the soft compound. If you're going to use street tires with the same compound, only wider on the back, you're just going to be spending more money for the same amount of traction, although they will wear longer.
I don't practice medicine. Can I ask you to stop practicing engineering?
What you say is true in ideal friction theory, but let's take simplistic look at just three aspects of this complex application. There are many more than three, but I'd have to write a small book, which I don't want to do. 1) the two surfaces (the tire and the ground) are not perfectly uniform.
You are correct in thinking friction is directly proportional to normal force, but that only applies to two uniform (smooth) surfaces. As soon as you have a rough surface, like a road, friction goes way up and is no longer directly proportional to normal force. 2) the tire would have to exhibit zero adhesion.
You've heard the term "sticky tires" and I'm sure you are familiar with the idea. Well, the "stickiness" also increases the friction and has a non-linear relationship with the force the resting tire is exerting on the road.
And then we have the tread. Tread significantly increases friction. The tread tends to tilt or curl as tangential force is applied to the ground. This causes an additional force normal to the pavement, causing friction to rise dramatically. This additional force is directly proportional to the surface area in contact with the road. 3) the rotational forces on the vehical can't be ignored.
As the vehicle is accelerating, it is trying to rotate. Imagine a car doing a wheely. The more friction enjoyed from numbers 1 and 2, the more accleration before the tires break loose and the more normal force from the rear tires. It's a series aiding feedback system.
Sorry, can't write any longer. I've got to scrub for surgery.
Last edited by Maika'i GXP : 12-24-2006 at 06:29 PM.
Don't forget the contact patch is dynamic. It grows in length as well as width and at lower tire pressures can get dramatically larger. Look at the way the wrinkle-wall slicks on a dragster squish down and spread out when they launch. Add (or multiply, actually) all the factors, contact patch growth, added friction due to heat buildup softening the rubber, weight shift transfering down force to the rear, and you get more GO. Bigger IS better, to a point.
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Quote:
Originally Posted by Hammerist
Don't forget the contact patch is dynamic. It grows in length as well as width and at lower tire pressures can get dramatically larger. Look at the way the wrinkle-wall slicks on a dragster squish down and spread out when they launch. Add (or multiply, actually) all the factors, contact patch growth, added friction due to heat buildup softening the rubber, weight shift transfering down force to the rear, and you get more GO. Bigger IS better, to a point.
There are many variables to consider.
Re-reading the original post, it is not clear what type of performance lil goat is looking for. If it's straight line acceleration on a flat road, a fatter tire in the rear would do well. If it's twisties, the same size tire, front and rear, would be best.
Re-reading the original post, it is not clear what type of performance lil goat is looking for. If it's straight line acceleration on a flat road, a fatter tire in the rear would do well. If it's twisties, the same size tire, front and rear, would be best.
No flame intended, but, there are too many comments like yours that tend to look like they are absolute and coming from fact, which is not the case. Let me start out by asking how many FTD's you have accumulated. Most FAST sports cars (viper, vette, porsche, Ferrari, lamborghini) have larger tires on the rear and they will never hit the drag strip. It all has to do with the car and where maximum traction and neutral handling meet. Enough is said, please refrain from comments that are not based on sound engineering principles or race experience.
Once again - no flame intended, please stick to hard true facts and engineering principles, otherwise it will mislead those looking for the right answer.
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Quote:
Originally Posted by Jack B
No flame intended, but, there are too many comments like yours that tend to look like they are absolute and coming from fact, which is not the case. Let me start out by asking how many FTD's you have accumulated. Most FAST sports cars (viper, vette, porsche, Ferrari, lamborghini) have larger tires on the rear and they will never hit the drag strip. It all has to do with the car and where maximum traction and neutral handling meet. Enough is said, please refrain from comments that are not based on sound engineering principles or race experience.
Once again - no flame intended, please stick to hard true facts and engineering principles, otherwise it will mislead those looking for the right answer.
OK, no flame.
How many FTDs? When I'm alone, every one.
This thread is talking about a Solstice being used on the streets. Nothing I've written in this thread has been about drag racing.
Comments based on sound engineering principles? You'll have to trust me, that's all I do. I'm an engineer pushing thirty years experience, multiple degrees and a state license.
I'll agree on the black and white, "absolute" feeling of my comments. Being "the boss" for so many years has unfortunately instilled a rather authoritarian quality to my writing. I recognize this. I'm rather new to on-line discussions (Sept of this year). Prior to becoming involved here, most of my e-mail writing was to people asking my professional opinion, my employees or as a customer of others. In all those circumstances, I'm the authority. It's a hard habit to break. A moment of inattention and suddenly everything is black and white and sounding like a new commandment.
Here's the basis of my comments.
I believe increasing weight of the back end of a rear wheel drive car that's already pretty much evenly balanced will make it under perform in the twisties due to the combined effect of increased moment and increased unsprung weight.
The extra unsprung weight will reduce road grip of the tires. Please remember my comments are in regard to often uneven streets, not smooth professional courses. The increased moment coupled with the loss of traction will send the rear out sooner and possibly unexpectantly, depending on the condition of the road in the turn.
I welcome your counterpoint. Nothing I say is absolute. If you have a differing opinion and can back it up, as you say, with sound engineering principles, I'll drop mine in a heartbeat and call yours my own. None of my opinions are sacred with me.
i just dont trust them after all the things happened with their suv tires and some of the other tires. when they did the recall on those tires you start to wonder about the other tires they produce for cars performance wise
