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I used to have a Supra (which also ran 25" tall tires). Definitely better tire selection and straight line traction when I went from a 315/25R19 to a 305/30R19.
Agreed, but I would say no-one who is concerned about performance goes to a 19" wheel period. Traction is not your concern when stepping upto a wheel size with NO selection, NO sidewall, and HEAVY HEAVY HEAVY.
They also make these cars look even more "lifted" than they already do. Suffice to say I am not a fan. Would love to have the tire choices available in the 26" tall selection, but hurts gearing, turn in response, ride height, and did I mention they are HEAVY.
Originally Posted by Steve Jarvis
Definitely another reason.
I used to have a Supra (which also ran 25" tall tires). Definitely better tire selection and straight line traction when I went from a 315/25R19 to a 305/30R19.
Agreed, but I would say no-one who is concerned about performance goes to a 19" wheel period. Traction is not your concern when stepping upto a wheel size with NO selection, NO sidewall, and HEAVY HEAVY HEAVY.
They also make these cars look even more "lifted" than they already do. Suffice to say I am not a fan. Would love to have the tire choices available in the 26" tall selection, but hurts gearing, turn in response, ride height, and did I mention they are HEAVY.
Olemiss540, while I agree with you in general about 19" wheels, I wouldn't be so narrow minded in your position on 26" overall diameter tires, whether 18 or 19. There are solid reasons to go that way and a number of track rats on our boards have.
At certain modification and power levels, the stock tire sizing is inadequate, in both width and overall diameter. Taller tires have a larger contact patch. And the taller gearing may actually be an advantage for high power levels.
This is why you'll find specific threads like this one talking about mods for fitting 26" tires under the wells for track use.
Sorry if I come off condescending, and I am NOT trying to be narrow minded. I am just speculating that the reason people move to 26" tall tires is because of the selection of wide tires in 25" heights, not because they prefer a 26" tall tire. You can have the same contact patch as a 26" tire with better gearing with the appropriate width/ratio tire, but they are NOT available. Taller tires are never a better option from my experience on anything but a drag strip, as gearing, turn-in, and weight are much more important (again: in my experience). I will read into the link you sent and appreciate the info!
Having not tracked (or prepared my car for track) the 996 platform, I very well may be way off base and love to learn!
Originally Posted by pteck
Olemiss540, while I agree with you in general about 19" wheels, I wouldn't be so narrow minded in your position on 26" overall diameter tires, whether 18 or 19. There are solid reasons to go that way and a number of track rats on our boards have.
At certain modification and power levels, the stock tire sizing is inadequate, in both width and overall diameter. Taller tires have a larger contact patch. And the taller gearing may actually be an advantage for high power levels.
This is why you'll find specific threads like this one talking about mods for fitting 26" tires under the wells for track use.
Honestly, I think most people are just trying to find good tires that fit the car one way or another. Even in 18", people have a tough time with the selection of tires available that fit the car and the way the awd is setup. Im personally going to be moving to a 26" because of the availability of the Potenza S-04s in that size.
Sorry if I come off condescending, and I am NOT trying to be narrow minded. I am just speculating that the reason people move to 26" tall tires is because of the selection of wide tires in 25" heights, not because they prefer a 26" tall tire. You can have the same contact patch as a 26" tire with better gearing with the appropriate width/ratio tire, but they are NOT available. Taller tires are never a better option from my experience on anything but a drag strip, as gearing, turn-in, and weight are much more important (again: in my experience). I will read into the link you sent and appreciate the info!
Having not tracked (or prepared my car for track) the 996 platform, I very well may be way off base and love to learn!
No ill feelings intended or taken. We're all here to share thoughts and learn. I don't disagree with what you're saying, and on a stock car, the stock sizes are likely the best
Just to clarify, a 25" tire with even the right tire size availability, does not have the same contact patch. A taller tire inherently has a (traction) advantage.
This is where my knowledge gets "blurry", but if you have a wide enough selection, you can get a larger (or same size) contact patch from a shorter tire while maintaining the other advantages stated for a shorter tire. For example:
On my track car, I run 275/40/17 NT-01's (since I LOVE NT-01's and they do not have a good selection of WIDE tires for my e36 BMW track car). My understanding is that even though these are TALLER, a 285/35/17 would have a larger contact patch, be a much better fit (shorter), provide better gearing, weigh less, and have better turn in response.
I dont understand why this is due to my lack of understanding of "contact patch", but I tradeoff turn-in/weight/and gearing to run NT-01's because of there amazing grip and cost (and the fact they dont make a better fitting size)! If I was advanced enough of a driver (and had loads of cash), I could run a hoosier, or the like in a 285/30/18, but sadly I have little of either.
Originally Posted by pteck
No ill feelings intended or taken. We're all here to share thoughts and learn. I don't disagree with what you're saying, and on a stock car, the stock sizes are likely the best
Just to clarify, a 25" tire with even the right tire size availability, does not have the same contact patch. A taller tire inherently has a (traction) advantage.
This is where my knowledge gets "blurry", but if you have a wide enough selection, you can get a larger (or same size) contact patch from a shorter tire while maintaining the other advantages stated for a shorter tire. For example:
On my track car, I run 275/40/17 NT-01's (since I LOVE NT-01's and they do not have a good selection of WIDE tires for my e36 BMW track car). My understanding is that even though these are TALLER, a 285/35/17 would have a larger contact patch, be a much better fit (shorter), provide better gearing, weigh less, and have better turn in response.
I dont understand why this is due to my lack of understanding of "contact patch", but I tradeoff turn-in/weight/and gearing to run NT-01's because of there amazing grip and cost (and the fact they dont make a better fitting size)! If I was advanced enough of a driver (and had loads of cash), I could run a hoosier, or the like in a 285/30/18, but sadly I have little of either.
your thinking too hard about it, larger diameter mean more rubber on the road. bigger circle means more touching to pavement.
take a 5" diameter balloon and put your hand on it and push it into table and measure how much touches now take a 10" balloon and measure how much touches the table.
I ran pilot sports, when I bought the car - - I swap to winter wheels/tires, which is good. Since summer tires/wheels can take some time-off - rear tires are gone, no life left. Front tires are still in good condition - So ill keep the front ones, until I find a good price for the rears. But since summer is around the corner.
I bought set of Sumitumo HTR Z-3 - rear 295/30ZR18 94Y - front 225/40ZR18 92Y XL - Whatever tirerack recommended- Since I do not track the car. OR go pedal to the metal. I'm going to give it a try. Some people say quiet some people say noisy, some say they suck in rain, some say it's ok, can't wait to put some miles on them and find out. Set of 4 - $512 - YES! you should never go with cheap tires - Putting flame suit on.
Let me try to clarify. The contact patch area is determined by the weight on the tire and the air pressure in the tire. The shape of the contact patch is determined more by the size of the tire.
The wider the tire, the wider the contact patch, but as the contact patch gets wider, is gets shorter front to rear. A taller tire will give you a longer contact patch front to rear, but the contact patch will get more narrow side to side.
A longer contact patch is better for straight line traction and a wider contact patch is better for cornering traction.
This all assumes you are being reasonable. If you stick a 165 on a 3,500 car, the sidewalls will now be supporting the weight instead of the contact patch and the basic assumptions are out the window.
I ran pilot sports, when I bought the car - - I swap to winter wheels/tires, which is good. Since summer tires/wheels can take some time-off - rear tires are gone, no life left. Front tires are still in good condition - So ill keep the front ones, until I find a good price for the rears. But since summer is around the corner.
I bought set of Sumitumo HTR Z-3 - rear 295/30ZR18 94Y - front 225/40ZR18 92Y XL - Whatever tirerack recommended- Since I do not track the car. OR go pedal to the metal. I'm going to give it a try. Some people say quiet some people say noisy, some say they suck in rain, some say it's ok, can't wait to put some miles on them and find out. Set of 4 - $512 - YES! you should never go with cheap tires - Putting flame suit on.
Be interested to know how they work out...please post a review after you get a few miles on them.
That's a great visual! Nice that you created that to help understand the concepts.
Given the same width tire, a taller tire will tend to elongate the contact patch front to rear. This is a better way to gain accel/decel traction then adding width!
While of course, taking advantage of width in any diameter tire, add corning ability.
It's probably too deep for the purposes of this tread. Contact patches can be very dynamic for the various loading possibilities on the tire. So while the visual is great to understand a static situation, one has to extrapolate beyond that. For example, a higher hp car, with stickier rubber, and more aero, can certainly create much more load on the tire to take advantage of - bigger donuts.
Yes, the visual is very basic. It's simply a starting point, that everything else builds on.
At the end of the day, tire compound/construction is king. I would take a set of 225 width "R" compounds over a set of 295 width all season tires any day for the track.
Later, Steve
Last edited by Steve Jarvis; Apr 8, 2016 at 11:23 AM.
Set of 4 - $512 - YES! you should never go with cheap tires - Putting flame suit on.
