Yes, I like that style. My old Trans Am had Cragar S/S wheels with extra fat wheels/tires in the back... it ruled back in the day. 
- Oct 10, 1999
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OMG redneck hot rod.Originally posted by: Crazyfool
Yes, I like that style. My old Trans Am had Cragar S/S wheels with extra fat wheels/tires in the back... it ruled back in the day.
Originally posted by: Iron Woode
you shouldn't put big tires on the back if your car doesn't need them. The big tires are for traction under a hard launch. That is what they are for. Not for handling. If big tires are needed for handling, then put them all around, not just on the back.Originally posted by: JulesMaximus
Just curious, what does your mopar weigh?
You said, "The point is for rear wheel traction on hard launches." To me, hard launches means drag racing. You don't do "hard launches" when exiting a corner.
What in my response to your post led you to believe I am or would ignore the front tires?
That is the point I am making. Balance.
edit: my mopar weighs 3400lbs without me in it.
I fail to see why you WOUDLN'T want as much grip as possible... throw some big tires on the back, and change spring rates or swaybar sizes to match.
Best of both worlds, for the most part.
I guess you didn't take physics in high school. the surface area difference provides virtually ZERO difference in grip. it's weight that's the key, hence people putting bags of sand in their trunk in the winter.
JulesMaximus
No Lifer
- Jul 3, 2003
- 74,578
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Originally posted by: Iron Woode
you shouldn't put big tires on the back if your car doesn't need them. The big tires are for traction under a hard launch. That is what they are for. Not for handling. If big tires are needed for handling, then put them all around, not just on the back.Originally posted by: JulesMaximus
Just curious, what does your mopar weigh?
You said, "The point is for rear wheel traction on hard launches." To me, hard launches means drag racing. You don't do "hard launches" when exiting a corner.
What in my response to your post led you to believe I am or would ignore the front tires?
That is the point I am making. Balance.
edit: my mopar weighs 3400lbs without me in it.
I didn't put larger tires on the rear of my car. It came that way from the factory.
You are so wrong about wider rear tires not helping with handling. How you accelerate out of a corner is critical for handling. Wider rear tires will help with that. They also help with hard launches on drag cars but that's a completely different animal than a car setup for road racing.
I do agree with you on balance though. That is also critical for good handling.
There are other factors that most people aren't aware of, such as scrub radius and side scrub - which is affected by the position of the centerline of the tire vs. an imaginary line drawn through the upper and lower balljoints to the pavement. A lower scrub radius results in better handling.
This is one reason a lof of newer cars have a ton of backspacing, such as the Corvette that was pictured. Backspacing is the distance from the inner side of the wheel hub to the plane of the inner rim lip. A lot of backspacing allows for the suspension and balljoints to be further inside the rim (outboard), thus decreasing scrub radius. It's the same deal with the Lambo, it just doesn't look like it (by the deep dished appearance of the rear rims) - half of the wheel is still inboard of the hub.
There's a lot of arguements out there on if more rubber is actually beneficial to handling. The general consensus is the more rubber the better. However, in certain situations it can be detrimental. For example, there simply may not be enough physical room under the front of that Lambo to put wider tires up there WITHOUT decreasing backspacing and bringing the rim out further (which would increase scrub radius - a bad thing). In addition to looking stupid (having a wheel that sticks out), it could actually hurt handling despite the inscreased tire width.
There are other factors such as the effect on steering. Too wide a front tire can cause the steering to track across ruts in the pavement, making the car feel unstable.
This is one reason a lof of newer cars have a ton of backspacing, such as the Corvette that was pictured. Backspacing is the distance from the inner side of the wheel hub to the plane of the inner rim lip. A lot of backspacing allows for the suspension and balljoints to be further inside the rim (outboard), thus decreasing scrub radius. It's the same deal with the Lambo, it just doesn't look like it (by the deep dished appearance of the rear rims) - half of the wheel is still inboard of the hub.
There's a lot of arguements out there on if more rubber is actually beneficial to handling. The general consensus is the more rubber the better. However, in certain situations it can be detrimental. For example, there simply may not be enough physical room under the front of that Lambo to put wider tires up there WITHOUT decreasing backspacing and bringing the rim out further (which would increase scrub radius - a bad thing). In addition to looking stupid (having a wheel that sticks out), it could actually hurt handling despite the inscreased tire width.
There are other factors such as the effect on steering. Too wide a front tire can cause the steering to track across ruts in the pavement, making the car feel unstable.
Theoretically, the surface area makes zero difference, but that isn't the case in real life. The rubber of a tire conforms to the bumps in the road, and the more bumps being conformed to, the higher the traction. The coefficient of friction isn't really a constant. Why do you think racecars don't have 6" wide tires?
Evadman
Administrator Emeritus<br>Elite Member
- Feb 18, 2001
- 30,990
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You are correct. In a lab, given the same total weight and same surface, the coefficient of friction will increase as the surface area decreases.
However, the question of a race car having 6" wide tires overlooks all the tasks that a tire must do. Not only must the tire provide the maximum amount of grip (higher coefficient of friction) in order to put the power down, the tire must also have the least amount of rolling resistance possible, be able to disapate unwanted heat, be able to take the extreme amounts of centrifical force, and act as another gear. (the faster a tire rotates the more its diameter increases, thus acting a lot like a CVT transmission.)
There are also the forces applied when cornering (side loads). A tire must be able to 'lay flat' on the road to get maximum traction. If a corner is taken at too high a speed, the tire will either 'roll over itself' (basicly get a wrinkle in the tread area) and thus lose almost all traction, or, if the air pressure is high enough, the inside of the tire will lift from the pavement, and put the weight of the car on the outside non-tread area (sidewall) of the tire, also causing a loss of traction.
Anyway, I am just trying to point out that the lab != real life use.
Weight being the several thousand pounds that any car weighs.
Weight isn't a factor. There's already enough there to make tire width a factor.
Wider is better - even in the back. Contrary to some people opinions, the rear isn't just there for the ride (well, except where braking is concerned to a degree). Not enough tire in the back and it's going to oversteer at some point.
The only reason a Grand Am doesn't have 10" wide tires is because of cost, fuel mileage (too much rolling resistance), and poor wet weather performance (hydroplaning).
That said, I don't like muscle cars with huge rubber back there (unless it's a 10 sec strip car). I think it looks stupid. I like a fairly even aspect ratio front to rear (with more width in back), with just the slightest rake.
Also, somebody mentioned tires "rolling over" because they're too wide. Not the case unless the rim it's mounted on is too narrow, or you're running too high an aspect ratio (70 series vs. 50 series for example). If you have the proper width rim and pressure that doesn't happen. They just break loose from loss of traction.
BTW, there are numerous racing series that have restrictions on tire width in order to reduce speeds.
Twista
Diamond Member
- Jun 19, 2003
- 9,646
- 1
- 0
only on sport cars.
ie: mustangs ;]
pics- wide meat 315 on rear (355 looks nice also)
http://i28.photobucket.com/albums/c212/MrCakes132/tires1.jpg
http://i28.photobucket.com/albums/c212/MrCakes132/tires2.jpg
http://i28.photobucket.com/albums/c212/MrCakes132/tires3.jpg
http://i28.photobucket.com/albums/c212/MrCakes132/tires4.jpg -best picture lol
cars
http://img238.imageshack.us/img238/6604/dsc020330ms.jpg
http://www.ninosport.com/ProductImages/ninosport_99-04tblo.jpg
http://i48.photobucket.com/albums/f249/gregm0203/yup5.jpg
ie: mustangs ;]
pics- wide meat 315 on rear (355 looks nice also)
http://i28.photobucket.com/albums/c212/MrCakes132/tires1.jpg
http://i28.photobucket.com/albums/c212/MrCakes132/tires2.jpg
http://i28.photobucket.com/albums/c212/MrCakes132/tires3.jpg
http://i28.photobucket.com/albums/c212/MrCakes132/tires4.jpg -best picture lol
cars
http://img238.imageshack.us/img238/6604/dsc020330ms.jpg
http://www.ninosport.com/ProductImages/ninosport_99-04tblo.jpg
http://i48.photobucket.com/albums/f249/gregm0203/yup5.jpg
- Oct 10, 1999
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I never said wider tires don't help handling. I said wider tires only on the back won't improve your handling. Put them all around for better handling, that is what I said.Originally posted by: JulesMaximus
Originally posted by: Iron Woode
you shouldn't put big tires on the back if your car doesn't need them. The big tires are for traction under a hard launch. That is what they are for. Not for handling. If big tires are needed for handling, then put them all around, not just on the back.Originally posted by: JulesMaximus
Just curious, what does your mopar weigh?
You said, "The point is for rear wheel traction on hard launches." To me, hard launches means drag racing. You don't do "hard launches" when exiting a corner.
What in my response to your post led you to believe I am or would ignore the front tires?
That is the point I am making. Balance.
edit: my mopar weighs 3400lbs without me in it.
I didn't put larger tires on the rear of my car. It came that way from the factory.
You are so wrong about wider rear tires not helping with handling. How you accelerate out of a corner is critical for handling. Wider rear tires will help with that. They also help with hard launches on drag cars but that's a completely different animal than a car setup for road racing.
I do agree with you on balance though. That is also critical for good handling.
you need to read better.
edit: seems you misunderstood my previous post. I was talking about a person that puts a pair of huge rear tires on because he thinks its cool. He/she does it to help it launch better and for looks. I wasn't talking about your car. Just older RWD cars.
Fenixgoon
Lifer
- Jun 30, 2003
- 33,275
- 12,838
- 136
uh, yeah weight is a factor... ever heard of a moment of inertia? bigger tires = higher rotational inertia = more energy wasted in getting the tires to rotate
as far as weight over the tires, friction is based on how much weight is in contact with the surface. friction force = u N, where N is equal to MG. more mass you have on top of the tire, the greater its frictional force (all other things being equal). why do you think RWD cars slip more easily in snow?
Googer
Lifer
- Nov 11, 2004
- 12,576
- 7
- 81
Look at his homepage, he has two ferrari's, several BMW's, a Lamborghini, and exotic motorcycles!
http://www.jimmy540i.com/main.htm
High school physics is totally incorrect in this case, or at least incomplete. It's the same problem with their argument that cars cannot exceed 1g of grip.
They're forgetting the tires are not resting on a flat surface, but rather molding to a surface with peaks and valleys.
Sweet I'm gonna go put skinnies on the front of my FWD car and smoke the 1/4 mile... literally :roll:
Yes, I know about rotational mass, and unsprung weight. Even still, newer cars have bigger rims and lower profile tires, at the cost of weight. The trade-off in handling is worth it.
My response was to the poster who said larger tires in the rear don't effect handling, that because most of the weight is in the front, larger tires in the rear wont make a difference.
That is absolutely untrue. While there is more traction to be had in a front wheel drive car (because the drive wheels are over the heavy drivetrain), the rear wheels are not along "just for the ride". Because of weight transfer (due to acceleration or cornering) the rear tires suddenly become very important. If they weren't, then nobody would have gone to the trouble of developing a more expensive independant rear suspension as found on many of todays cars - if it was all about traction off the line then the straight axle is the perfect choice.
No he's not. Wider tires help with grip, up to a point. Handling is about what happens when you start to lose grip (which will inevitably happen, regardless of tire width) and if you understeer or oversteer. Wider rears will increase understeer and cause your car to go wide in the corner.
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