Who has wider tires than 275's?

[cyrus240sx]

Im just wondering because i have 275's and i think they look awesome,but i think i could go wider, and wanted to know how extreme are ppl going on their tire size?

pics would help too!

[Onizuka]

Holy Dead Hooker Batman! Thats what I call as set of meaty treads

[USsil80]

Holy Dead Hooker Batman! Thats what I call as set of meaty treads

i agree... that is awsome

[D1SR240]

What size tires did the RB26DETT powered S14 from Underground Motorsports have?

[USsil80]

285

[SoCalSilvia]

275's? bah! i laugh at you! you cannot compete with 355's!







I'm j/k 275 on an S14 is sweet, these 355's are on a Carrera turbo that I saw at the SoCalEuro meet

[USsil80]

ohh i was getting ready to say D@mn i need the specs on that rim with more dish than a china closet

[cyrus240sx]

yeah ive seen pics of tires for porsches.... they were pirelli rossos in 355-25-19and yes... it was a 25 sidewall

[TurboSilvia7587]

i went to the Apexi garage sale last weekend andf there was a s14 kouki with some 295's in the rear

[SmithSR]

Image is nothing. Max grip is everything. Get R compounds instead.

[Graphfixz]

these are 295

[spanishricer]

Im just wondering because i have 275's and i think they look awesome,but i think i could go wider, and wanted to know how extreme are ppl going on their tire size?

pics would help too!

Maybe it's just the angle of the pic...but your tires don't look that wide

[w1ngzer0]

to me that car looks horrid. Looks like it has 20's...... Ew...It just looks rediculous :barf

[SoCalSilvia]

Maybe it's just the angle of the pic...but your tires don't look that wide

I think its because he has high offset

[Nismo_Freak]

I have a 285 in the rear.

[chmercer]

obey your thirst. buy the 355s.

[TachyonS14]

Ya, that first picture doesn't look like he has that wide of a tire.

[[s3]]

Wider wheels do not necessarily provide better traction.

You're just slowing your car down.

[Onizuka]

They help you drive across small lakes better

[cyrus240sx]

yeah they dont look that wide.... ill take another pic thats more from behind so you can see..... and yes that s13 with the 295 stretched where a 335 or larger tire should be just looks wierd

[cyrus240sx]

yes they have slowed my car down a little.... but the added grip that ive noticed from they offsets the speed loss. i also really like the fact that my tires are flush with side of my car now.if i really wanted to i could have put a 225 tire on the 9.5 inch rim but i hate the stretched look

[xyoufailmex]

Psh, JDM stretched tire style here yo! Cheaper, and easier to slide with on my weak little KA24E... If you are running huge friggin tires and arent making 225 or so to the wheels, whats the point?

[Nismo_Freak]

]Wider wheels do not necessarily provide better traction.

You're just slowing your car down.

Wider wheels allow for wider tires which has the equal amount of possibility to allow for greater traction.

[Nismo_Freak]

Psh, JDM stretched tire style here yo! Cheaper, and easier to slide with on my weak little KA24E... If you are running huge friggin tires and arent making 225 or so to the wheels, whats the point?

You know... there is something apart from drifting that some people engage in.

It's a performance based autosport that we call racing, it involves such things as braking, accelerating, and actual road handling on a course... you should look into it.

You know that sport that has been around for nearly a hundred years?

[[s3]]

Here's an article from Genic, one of the TT.net regulars. Interpret it however you want.

_________________________________________________Fat or thin? The question of contact patches and grip.

If there's one question guaranteed to promote argument and counter argument, it's this : do wide tyres give me better grip?

Fat tyres look good. In fact they look stonkingly good. In the dry they are mercilessly full of grip. In the wet, you might want to make sure your insurance is paid up, especially if you're in a rear-wheel-drive car. Contrary to what you might think (and to what I used to think), bigger contact patch does not necessarily mean increased grip. Better yet, fatter tyres do not mean bigger contact patch. Confused? Check it out:

Pressure=weight/area.

That's about as simple a physics equation as you can get. For the general case of most car tyres travelling on a road, it works pretty well. Let me explain. Let's say you've got some regular tyres, as supplied with your car. They're inflated to 30psi and your car weighs 1500Kg. Roughly speaking, each tyre is taking about a quarter of your car's weight - in this case 375Kg. In metric, 30psi is about 2.11Kg/cm2.

By that formula, the area of your contact patch is going to be roughly 375 / 2.11 = 177.7cm2 (weight divided by pressure)

Let's say your standard tyres are 185/65R14 - a good middle-ground, factory-fit tyre. That means the tread width is 18.5cm side to side. So your contact patch with all these variables is going to be about 177.7cm2 / 18.5, which is 9.8cm. Your contact patch is a rectangle 18.5cm across the width of the tyre by 9.8cm front-to-back where it sits 'flat' on the road.

Still with me? Great. You've taken your car to the tyre dealer and with the help of my tyre calculator, figured out that you can get some swanky 225/50R15 tyres. You polish up the 15inch rims, get the tyres fitted and drive off. Let's look at the equation again. The weight of your car bearing down on the wheels hasn't changed. The PSI in the tyres is going to be about the same. If those two variables haven't changed, then your contact patch is still going to be the same : 177.7cm2

However you now have wider tyres - the tread width is now 22.5cm instead of 18.5cm. The same contact patch but with wider tyres means a narrower contact area front-to-back. In this example, it becomes 177.7cm2 / 22.5, which is 7.8cm.

Imagine driving on to a glass road and looking up underneath your tyres. This is the example contact patch (in red) for the situation I explained above. The narrower tyre has a longer, thinner contact patch. The fatter tyre has a shorter, wider contact patch, but the area is the same on both.

And there is your 'eureka' moment. Overall, the area of your contact patch has remained more or less identical. But by putting wider tyres on, the shape of the contact patch has changed. Actually, the contact patch is really a squashed oval rather than a rectangle, but for the sake of simplicity on this site, I've illustrated it as a rectangle - it makes the concept a little easier to understand. So has the penny dropped? I'll assume it has. So now you understand that it makes no difference to the contact patch, this leads us on nicely to the sticky topic of grip.

The area of the contact patch does not affect the actual grip of the tyre (strange though it may seem) but it does allow the tyre to distribute heat across the contact patch better, making their operational range greater. The things that affect grip are the coefficient of friction and the load on the tyre. Well we know from above that the load on the tyre remains pretty much the same. Of course it varies in corners as more weight is transferred because of cornering forces, but for the sake of simplicity, load is constant. That leaves on last factor - coefficient of friction. Friction is basically dependant on the rubber compound used to make the tyre, and how that compound changes it's coefficient of friction based on heat. Generally speaking, tyre rubber gets stickier the warmer it gets. At least to operating temperature, then it starts to overheat and it can all go pear-shaped. That's why my comment right at the top about heat dispersal on larger tyres is so important. That's also why Formula-1 teams have tyre-warmers in use before the tyres actually get put on the cars. The rubber compound that's in your tyres is something you'll only be able to find out by calling a tyre dealer, or the manufacturer. But the equation you need to know is simple :

softer rubber = quicker wear = shorter tyre life.

Generally speaking, that's why fatter tyres are generally regarded to have more grip - they're normally made of a softer rubber compound with a higher coefficient of friction. It's nothing to do with contact patch size after all.

I can tell you're still thinking about this. And the question bubbling around your head now is this:

Why doesn't friction depend on surface area?

Well, although a larger area of contact between two surfaces would create a larger source of frictional forces, it also reduces the pressure between the two surfaces for a given force holding them together. In this case, gravity is the force holding your car on the road. As I told you above, pressure = weight / area. So it works out that the increase in friction generating area is exactly offset by the reduction in pressure; the resulting frictional forces, then, are dependent only on the frictional coefficient of the materials and the force holding them together. If you were to increase the force as you increased the area to keep pressure the same, then increasing the area would increase the frictional force between the two surfaces.

In laymans terms : the weight of your car isn't changing - that's the force keeping your tyre pressed against the road. The contact patch area doesn't change - I've explained that above. Your tyre isn't changing it's coefficient of friction (unless something is going badly wrong). To get more grip, you need to increase the force as well as the coefficient of friction. This is exactly what you see in Formula 1. Wings on the car increase the pressure on the tyres as the car goes faster, and the rubber compound in the tyres increases it's coefficient of friction as they get hotter. That equates to massive grip in the corners and ground-hugging speed on the straights. In fact the wings on an F1 car generate so much extra downforce that it more than doubles the weight of the car. In real terms, that means if someone built a racing track upside down, you could race Formula 1 cars on it and they'd stick to the track because the downforce is greater than the weight of the car under gravity. Neat eh?

That last paragraph also explains why dynamic setup on your car is pretty important. All the theory I've gone through so far is based on a static system - the car is driving at a constant speed in a straight line. In reality of course, the contact patch is effectively spinning around your tyre at some horrendous speed. When you brake or corner, load-transfer happens and all the tyres start to behave differently to each other. This is why weight transfer makes such a difference the handling dynamics of the car. Braking for instance; weight moves forward, so load on the front tyres increases. Pressure stays the same, so by your newly-learned formula, the contact patch area must increase. Using a bastardised version of the friction theory, the same load-per-m2 of contact patch, but more contact patch = more grip. The reverse happens to the rear at the same time, creating a car which can oversteer at the drop of a hat. The Mercedes A-class had this problem when it came out. The load-transfer was all wrong, and a rapid left-right-left on the steering wheel would upset the load so much that the vehicle lost grip in the rear, went sideways, re-acquired grip and rolled over. (That's since been changed.) The Audi TT had a problem too because the load on it's rear wheels wasn't enough to prevent understeer which is why all the new models have that daft little spoiler on the back.

If your brain isn't running out of your ears already, then here's a link to a raging debate that happened in 2000 on one of the Subaru forums about this very subject. If you decide to read this, you should bear in mind that Simon de Banke, webmaster of ScoobyNet, is a highly respected expert in vehicle dynamics and handling, and is also an extremely talented rally driver. It's also worth noting that he holds the World Record for driving sideways...........

If you decide to fatten up the tyres on your car, another consideration should be clearance with bits of your car. There's no point in getting super-fat tyres if they're going to rub against the inside of your wheel arches. Also, on cars with McPherson strut front suspension, there's a very real possibility that the tyre will foul the steering linkage on the suspension. Check it first!

[onosqv]

Nice article [s3], but from what I read of it (I got a little lazy), it seems to be talking of different sized tires on the same width wheel.

I think Nismo_Freak is mentioning wider wheels + wider tires in general, in which the contact path remains a rectangle, as referred to by the article. So basically, just get tires that are made for the wheel

Of course if you put a too large a tire on a wheel that isn't made for it, it won't really make it better. And if you put too small a tire, contact path would start getting a little worse too (hence, drifting w/ these bad boys? )

[Nismo_Freak]

Nice article [s3], but from what I read of it (I got a little lazy), it seems to be talking of different sized tires on the same width wheel.

I think Nismo_Freak is mentioning wider wheels + wider tires in general, in which the contact path remains a rectangle, as referred to by the article. So basically, just get tires that are made for the wheel

Of course if you put a too large a tire on a wheel that isn't made for it, it won't really make it better. And if you put too small a tire, contact path would start getting a little worse too (hence, drifting w/ these bad boys? )

No, he is stating simple facts about how the tires work.

Another arguement you can throw into the mix is load index which is a all too common point that Q45Tech brings up. You also need to take into account such things as void ratio of the tread, tread squirm, etc.

Genic is meerly making a point of reality, however don't take it all to heart and run out there and buy some 195/60/15's in an R-compound and expect to be on par with a GT car, and by the same token don't run out there and slap a set of 335/35/18 tires on all 4 corners. The key is finding a particular load index and tire sizing for your vehicles dynamic force, and then picking up that sizing in the stickiest compound out there.

[xyoufailmex]

Sure, and I was obviously kidding and Im positive thats obvious to anybody with half a brain. So, all smart *** comment aside...

Wider isnt necessarily better. Fact is we aren't playing gran turismo and we dont have unlimited funds... Its senseless to pay more for 275 tires and get cheap ones, when you can spend the same and get nice soft and Theres a reason our cars aren't designed like steamrollers...

[chmercer]

haha. you guys think too much. like 5% of the people on this board could actually tell the difference between a 275 and a 285 tire. if you want a big tire then go buy it. its not really gonna matter. everyone knows that a 355 tire in a crappy street compound like a p zero is going to suck, and if you dispute this, you got somthing screwed up in your head. but it sure does look cool. and im sure thats what that guy with the porsche was thinking when he gave the guy at discount 500$ for his one tire.

[Structure240sx]

you're exactly right. street tires are just crap when trying to hold real power. i have nitto 555r type II raod race tires for the street 275/40/17 now and they are holding great compared to the kumho mx's