I need a front wheel size blessing. I have done my research. Need green light.

[InsanityInc]

Because the 911 definitely weighs 2700lbs, doesn't it?

Go read up on load ratings and contact patch size. Also, I said it might be stretched. If it isn't, whatever, it fits fine on a 7" so why go with an 8"?

[InsanityInc]

Oh, and also, to give you people an idea, the Porsche 911 Carrera S runs 235mm tires in the front, and weighs 3131 pounds, or about 400lbs more than an s13. Still think you need massive tires on the front of your s13? 225mm fronts are fine, I'd say they're probably the ideal size for an s13, and they'll fit fine on a 7" wide wheel.

[Mykl]

let us know when you find out the rear wheel size

you tell us if you want it fat, square, or stretched, or in between 2, and with the wheel size we can tell you what youll be able to run, and what the front wheel/tire combo can be

Will do. Aside from responding to posts I'm going to refrain from asking any more questions until I have the car and can provide more information.

After reading the advice you guys are giving me and searching for wheels other than the P1's I'm seeing exactly why the five lug thing is so popular.

An 8 inch wide wheel is excessively large. After a certain point of tire widening, the traction gains are very minimal and can actually end up hurting by adding more weight than gained performance,. Ever wonder why road race cars don't all have 12" wide wheels with crazy wide tires on them? There's a reason. You might need an 8" wide wheel for something heavier, or on the drive wheels if you have a LOT of power, but for a 2700 pound car on the front? No point.

A 225mm tire will fit fine on a 7" wide wheel. 1" is roughly equal to 25mm (24.7 exactly I think). 205mm fits fine on a 6", so obviously a 1" wider tire will be fine on a 1" wider wheel.

All you'd be doing by going to a 8" wheel with the same tire is adding weight for no reason, and spending more on the wheels. Heck, it might even end up stretched on the 8" which is AWFUL for performance, safety and tire life.

My car isn't even off the boat yet and it already has over 200 whp. While 8" may be more wide than is necessary for a BPU + Power FC SR, when I bolt up a Disco Potato the 8" wide wheels may allow me to go to a 235 for even more rubber up front.

There's no way a 225mm wide tire is going to be stretch on a 203mm wide wheel. That's as close to a perfect fit as it gets.

I understand your arguement, but my car will have enough power to use the extra width. Also consider that the wheel I'm buying isn't available in a 17x7" in anywhere near the offset it's suggested that I need.

[InsanityInc]

I understand your arguement, but my car will have enough power to use the extra width.

So you have one of those rare FWD 240s? Your horsepower has nothing to do with your front tire size unless your car drives with the front wheels. The weight of your car and the braking requirements have everything to do with front tire size. Anything more than what you need is just extra weight, and will actually inhibit performance by adding unsprung weight and screwing up your contact patch.

[Mykl]

So you have one of those rare FWD 240s? Your horsepower has nothing to do with your front tire size unless your car drives with the front wheels. The weight of your car and the braking requirements have everything to do with front tire size. Anything more than what you need is just extra weight, and will actually inhibit performance by adding unsprung weight and screwing up your contact patch.

Wow, this is incredible. I bet you're also one of those guys who says that it's stupid to have a rear spoiler on a FWD car.

So why don't I just run bicycle tires? You don't think having wider wheels and tires will allow me to corner at higher speeds? You don't think I'll be able to reduce my stopping distances with wider wheels and tires? Don't you think that with more power I'm kinda need that extra ability to fight against the increased time I'll be on my brakes to cope with the extra momentum?

Let me break it down... on a race track, if you have more power, you have higher straight away speeds. Since you're going faster when you start braking, you have to start braking earlier to cope with the extra momentum. With more rubber up front, you can maintain more momentum and slow down faster, which means you spend less time on the brakes. This means faster lap times.

I can't make it easier to understand. I hope you get it.

[InsanityInc]

I can't make it easier to understand. I hope you get it.

You have a half-assed understanding of what's going on.

Increasing the width of your tire doesn't necessarily increase the area of the contact patch substantially, as the contact patch shape is due to the weight of the car and for any given dimensions a square will have the largest area as opposed to a rectangle. In other words, to maximize contact patch area gain from tire width increase, you do not want to exceed a square.

Therefore, increasing your contact patch SOME (going from 205-225, for example) is a GOOD idea. Increasing your contact patch by a ridiculous amount (205-255, for example) is a BAD idea. You gain very little contact patch area from the additonal width, and not only does the tire itself weigh more, so does the wider required wheel. And in fact, the minimal contact patch gain won't even offset the weight gain and your car will handle worse.

Geometry: It's your friend.

Besides, if you know everything there is to know about tires, why the **** are you asking for advice?

[Mykl]

You have a half-assed understanding of what's going on.

Increasing the width of your tire doesn't necessarily increase the area of the contact patch substantially, as the contact patch shape is due to the weight of the car and for any given dimensions a square will have the largest area as opposed to a rectangle. In other words, to maximize contact patch area gain from tire width increase, you do not want to exceed a square.

Therefore, increasing your contact patch SOME (going from 205-225, for example) is a GOOD idea. Increasing your contact patch by a ridiculous amount (205-255, for example) is a BAD idea. You gain very little contact patch area from the additonal width, and not only does the tire itself weigh more, so does the wider required wheel. And in fact, the minimal contact patch gain won't even offset the weight gain and your car will handle worse.

Geometry: It's your friend.

Besides, if you know everything there is to know about tires, why the **** are you asking for advice?

Alright man... how hard is it to understand that a wider wheel can hold a wider tire? I may not need the extra tire width right now, but in the future I may want a wider tire. This means that I save money because I don't have to go out and buy a different set of wheels when I want to try to increase width of the tire. I might have to play with spacers and do some fender modifications, but that costs a lot less than new wheels.

1st grade math: It's your friend.

I'm asking for advice CONCERNING WHAT FITS ON THIS CAR. I was looking for somebody to tell me if the wheel and tire combo I had selected will actually fit the car. I didn't ask for an education.

I think you need to stop posting in this thread before I develop a negative opinion of you. I don't appreciate your efforts to turn the conversation into a train wreck by insulting my intelligence. Your advice is no longer welcomed.

[InsanityInc]

Alright man... how hard is it to understand that a wider wheel can hold a wider tire? I may not need the extra tire width right now, but in the future I may want a wider tire.

I'm pointing out that this argument is irrelevant because you will never need a wider front tire in the future. Ever.

[Mykl]

I'm pointing out that this argument is irrelevant because you will never need a wider front tire in the future. Ever.

Fair enough.

When you can convince these guys that they don't need as much rubber as they have on this car...

http://www.pdm-racing.com/features/240sx4.html

...I won't think twice about your opinion on the subject. You'll hear no more arguements from me.

[naed240sx]

Argueing with Insanity is pointless. Everybody has gotten used to pretty much just ignoring him.

[InsanityInc]

Fair enough.

When you can convince these guys that they don't need as much rubber as they have on this car...

http://www.pdm-racing.com/features/240sx4.html

...I won't think twice about your opinion on the subject. You'll hear no more arguements from me.

Read a little deeper and you'll see why they did it:

Quote »Next up was the CACC Canadian National Autoslalom in Red Deer, Alberta in the beginning of August. So it was decided to revamp the front suspension a bit to add more grip to compensate for the understeer. Eventually, front wheels were upped to 10” also with 275/40/17 tires. [/quote]Due to the large amount of power the car was putting down in a relatively light car, the rear tires had to be quite large. There's really no way around that, but for that purpose the extra weight on the drive wheels will actually help to reduce wheelspin, as well as the marginally greater grip. However, when your rear tires are that big, you're going to understeer. So, in order to compensate for it they just went bigger on the front tires. In all honesty, I find that to be a fairly poor solution for a few reasons:

1) Bigger tires in front will reduce the effect that camber has.2) Bigger front tires = worse turning response, and of course more unsprung weight.3) The understeer could have been banished much more effectively without adding weight.

It says they attempted to revamp the front suspension, when in reality they should have been focusing on the rear. If your rear is causing understeer due to big tires, stiffen up the rear suspension. Also, their overly large front tire choice (245) was already reducing the effects of camber. By going to a smaller tire, more camber, a stiffer rear suspension and possibly a softer front (if necessary), they could have achieved the same effect without modifying the body as much as they did, and would have saved weight doing it.

This brings me back to the 911, really. The 911 has 295mm tires on the rear to handle the power and the rear biased weight distribution, and it has only 235mm tires on the front, yet I don't think anyone will ever accuse the 911 of UNDERSTEER. Quite the contrary.

[hazw8st]

So, you want the whole 8 inches, huh?

[InsanityInc]

To back up what I say about their tire choices being fairly poor, here's some factory tire sizes from cars which I'm sure you would agree handle quite well:

Ferrari 360: 215mm F 275mm R2003 M3 Coupe: 225mm F 255mm RLotus Elise: 195mm F 225mm R

Honestly, if front tires 225mm or smaller are good enough for Ferrari, BMW Ms and Lotus, they ought to be good enough for a 240sx.

[McRussellPants]

Insanity Inc go smoke your hooka eslewhere.

Ever wonder why road race cars don't all have 12" wide wheels with crazy wide tires on them? There's a reason. .

Yeah, class restrictions retard. Prototype, F1, JGTC, Even the stupid carbed KA24E SCCA cars had ****ing steam rollers.

Everyone who buys that stupid "wider tires don't help handling" either autocrosses or just parrot off the people that do. Wider tires don't help autocross since you can't get enough heat into them due to autocross being lame and 5minutes of lap time over 5hrs isnt gonna cut it on anything other than a 225 on a 2700lb car.

This brings me back to the 911, really. The 911 has 295mm tires on the rear to handle the power and the rear biased weight distribution, and it has only 235mm tires on the front, yet I don't think anyone will ever accuse the 911 of UNDERSTEER. Quite the contrary.

Wow, what a logical arguement sir. Since a car with 40/60 rear distribution and a huge rear polar moment runs 235/s in the front - that means that a 240SX should to. You have me convinced sir. What a genius.

You complain about all this crap "Bigger front tires = worse turning response" The only way bigger tires will have less response is that if you have grandma spring rates that won't load the tires quickly.

Cliff Notes: Autocrossing setup is entirely different than track car setup. This is due to A) Autocross is going 30mph in a parking lot and B) 1 minute laps with 20 minutes inbetween each one will not put any sustained heat into the tires.

Racecars run steamrollers since they can get enough heat into the tires to use them. The only reason race cars don't run 12in wide wheels is due to restrictions in one area or another (motor restrictions amount to not needing them, and then theres the actual size limitations)

[McRussellPants]

To back up what I say about their tire choices being fairly poor, here's some factory tire sizes from cars which I'm sure you would agree handle quite well:

Ferrari 360: 215mm F 275mm R2003 M3 Coupe: 225mm F 255mm RLotus Elise: 195mm F 225mm R

Honestly, if front tires 225mm or smaller are good enough for Ferrari, BMW Ms and Lotus, they ought to be good enough for a 240sx.

Woah, even more infinte wisdom. 195tire good enough for a car that curbs 2000lbs = good enough for a car that curbs 2700. 215 on the front of a ferrari, awesome, I can run a 215 tire in the front now... I better get to work moving my engine into the hatch.

M Coupe... whoa a toughy. you actually stumbled upon a car that has a similar setup to the 240SX.... But then theres the fact that the M3 was designed to be a race car and the 240SX was designed to get grocerys... Also the fact that alot of the modded M3s I've seen run 245+ front tires.

[Mykl]

Argueing with Insanity is pointless. Everybody has gotten used to pretty much just ignoring him.

Yeah, I think I'm going to join the rest of you guys and just ignor him. Somehow I get the feeling that he's never even been to an autocross, much less a race track.

You argue with the guy and he swears up and down that you're wrong, you show him an example of a car built buy guys who know what the heck they're doing proving him otherwise... and then he calls you wrong while agreeing with what you were just saying? How can you talk to a guy like that?

Besides... he says it's OK because that car has a lot of power. So when I bolt up my upgraded turbo and I'm pushing close to the same amount of horsepower my car will handle worse if I use wider tires? I don't understand this logic.

[InsanityInc]

Woah, even more infinte wisdom. 195tire good enough for a car that curbs 2000lbs = good enough for a car that curbs 2700. 215 on the front of a ferrari, awesome, I can run a 215 tire in the front now... I better get to work moving my engine into the hatch.

You do realize that I've been saying FOR THE ENTIRE THREAD that non-drive tire size requirement is almost completely dependent on vehicle weight, right?

My point was that if wider tires make your car handle so much better, than why do ferrari, Lotus and BMW not use a really really wide tire up front? There is a reason for it, and I've tried explaning it but people apparently don't care about physics or geometry.

Quote »Yeah, class restrictions retard. Prototype, F1, JGTC, Even the stupid carbed KA24E SCCA cars had ****ing steam rollers.[/quote]And all of those run SLICKS, not RADIALS. You can get away with a larger tire on slicks because you can run a MUCH LOWER tire pressure safely, which will enlongate the contact patch in the Y direction, so a much wider tire can be used to achieve a square (maximum gain) contact patch.

Quote »Besides... he says it's OK because that car has a lot of power. So when I bolt up my upgraded turbo and I'm pushing close to the same amount of horsepower my car will handle worse if I use wider tires? I don't understand this logic.[/quote]I take it you didn't read my post? Their front tire size choice SUCKS, they would be better off using smaller ones. Their REAR tire size choice is a necessity due to the rear tires being the drive wheels, and the ones that actually handle the power. Their front tire sizing is an extremely poor patchwork fix for the understeer caused by the large rear tires.

Jesus christ people, READ.

[Mykl]

I take it you didn't read my post? Their front tire size choice SUCKS, they would be better off using smaller ones. Their REAR tire size choice is a necessity due to the rear tires being the drive wheels, and the ones that actually handle the power. Their front tire sizing is an extremely poor patchwork fix for the understeer caused by the large rear tires.

Jesus christ people, READ.

I can't maintain a discussion with somebody who is incapable of thinking logically.

[naed240sx]

Hahah I wish sombody would just ban him. You should read some of his exhaust discussion threads. If you think he has strong feelings about tire sizing, wait till you hear his shpeal on exaust sizing.

[Mykl]

Hahah I wish sombody would just ban him. You should read some of his exhaust discussion threads. If you think he has strong feelings about tire sizing, wait till you hear his shpeal on exaust sizing.

He gave his opinion, rudely, nobody agrees... and now I just wish he would go away. I really don't want to have to create a new thread to ask another question on this subject because this one turned into a trainwreck.

[InsanityInc]

Hahah I wish sombody would just ban him. You should read some of his exhaust discussion threads. If you think he has strong feelings about tire sizing, wait till you hear his shpeal on exaust sizing.

Sorry, but dyno readings prove me right. 2.5" produces less power across the entire range as opposed to 3". I really don't understand how you can argue with dyno graphs.

Quote »I can't maintain a discussion with somebody who is incapable of thinking logically.[/quote]How is that not logical? More weight makes your car handle worse, adding tire/wheel width adds weight, so unless the amount of traction gained offsets the amount of weight gained, your car will handle worse. If you think that isn't logic, here, let me put it into logical symbols for you (although I seriously doubt you'll know what any of them mean):

H = improved handlingW = added weightT = added tractionY = bigger tires

W->¬HT->HY->(W^T)iif(W > T) Y->¬Hiif(W < T) Y->H

Good enough logic for you?

[Mykl]

How is that not logical? More weight makes your car handle worse, adding tire/wheel width adds weight, so unless the amount of traction gained offsets the amount of weight gained, your car will handle worse. If you think that isn't logic, here, let me put it into logical symbols for you (although I seriously doubt you'll know what any of them mean):

H = improved handlingW = added weightT = added tractionY = bigger tires

W->¬HT->HY->(W^T)iif(W > T) Y->¬Hiif(W < T) Y->H

Good enough logic for you?

Um yeah, whatever dude.

[naed240sx]

Sorry, but dyno readings prove me right. 2.5" produces less power across the entire range as opposed to 3". I really don't understand how you can argue with dyno graphs.

Im not arguing that point. I agree. I am just pointing out that you make wayy to big of a deal out of everthing and really enjoy arguing for the sake of arguing. Often your reasoning is flawed or missing important details.

[McRussellPants]

Blah blah blah I like to parrot things off the bowels of the interent..

Any race car runs the largest tire it can either fit or restricted to.

Every car will handle better with wider tires. Id say 99% of the time as long as it will fit in the stock fender it will handle better.

Saying 8in wide on a 240SX is stupid makes your opinion invalid.

If anything you were saying were true, preformance front engined cars would not be running 9in wide wheels all the way around. They would be running 6.5fronts and 10in wide rears. But oh yeah... thats ****ing stupid.

Despite whatever FAQ you read off of the bowels of the internet wider tires do make your car handle better. Anyone whos actually driven a car further than the grocery store knows this.

on an unrelated note.

3in makes more power on the dyno, but everyone I've talked to says the 2.5 feels much better while driving.

In Conclusion - Get your *** off automotiveforums or whatever and go to any race ever (besides Showroomstock or forumla VW) and look at all the not cookie cutter tires. Then comeback and try to explain it off.

[nismofly]

i would have to say there is a point where the increased weight of the wheel / tire combo outweighs the handling advantage, but there no freaking way its 7 inches

[McRussellPants]

i would have to say there is a point where the increased weight of the wheel / tire combo outweighs the handling advantage, but there no freaking way its 7 inches

Its when the tires are so wide theres no way to get enough heat into them without plowin around at like 30degrees of slip angle.

There is the weight thing... but since a KA-T or SR isnt gonna have any problems pushing anything that will fit under metal fenders that may be more personal prefrence of when it starts feeling like *** over bumps.

[nismofly]

a better example would be speed world challenge, especially touring car

the cars are allowed to run up to a 17x8 wheel, and up to a 235/40/17 tire

notice i said up to, not have to

i know for a fact every team out there is running as much as they can

as for the whole those cars are on slicks thing, in world challenge these cars are running toyo ra-1's

[InsanityInc]

If anything you were saying were true, preformance front engined cars would not be running 9in wide wheels all the way around. They would be running 6.5fronts and 10in wide rears. But oh yeah... thats ****ing stupid.

Except that's exaclty what they do. Did you miss this?

Quote »Ferrari 360: 215mm F 275mm R2003 M3 Coupe: 225mm F 255mm RLotus Elise: 195mm F 225mm RPorsche 911S: 235mm F 295mm R[/quote]Quote »Despite whatever FAQ you read off of the bowels of the internet wider tires do make your car handle better.[/quote]To a point. There are diminishing returns, and that's based on the tire pressure you can run and the weight of your car.

Quote »and look at all the not cookie cutter tires. Then comeback and try to explain it off.[/quote]Slicks and radials are a completely different ball game, I already explained why. But even with slicks there's a point of diminishing returns, it's just SIGNIFICANTLY larger than a radial. Plus, F1 cars which handle at ridiculous G levels and very high heats need tires with a huge load rating so they don't pop (and sometimes they still do).

[InsanityInc]

a better example would be speed world challenge, especially touring car

the cars are allowed to run up to a 17x8 wheel, and up to a 235/40/17 tire

notice i said up to, not have to

i know for a fact every team out there is running as much as they can

as for the whole those cars are on slicks thing, in world challenge these cars are running toyo ra-1's

What sort of cars are they? Generally touring cars are large cars, so I wouldn't be at all surprised to see them using a 235mm tire.

[nismofly]

ok i was comparing tires with touring car because theyre around the size of the 240

you want the big cars, for GT class, the vipers run 18x11 front 18x13 rear with a 275/335 tire combo...porsche RSR's are allowed 18x10 front and 18x12 rear with a 245/305 tire combo, and the volvos are awd so they get 18x11 all around with 305 tires

everything else runs 18x11 front, 18x12 rear, with a 275/335 tire set...and you know theyre all running that max

i can even link to WC appendix A if you want to see for yourself

http://www.scca.com/_FileLibra...x.pdf