[why?]

Originally Posted by mrg666

I am not aware, did anybody say that? I think the "crowd", as you call them, mainly thinks that wider looks better. I haven't seen anybody looking at those skinny tires with admiration and telling each other how smart their owners should be and they should know something that everybody else missed. You guys are not that smart, "crowd" is not that stupid. Just install those wide tires and you will feel better, I promise.

several people have. The looks crowd really isn't germain, even though one can hope to try and get them to not buy the biggest 18" wheels and tires they can cram onto the car.

Has nothing to do with who is smart. It has to do with having a conversation and exchanging ideas. It seems most people that track twins have decided 245 or 255 17's are the way to go. While the larger auto community is all trying to cram at least 18's on everything, including lightweight cars like the miata and the twins. It is worth having a discussion about even smaller wheels and tires. When the miata came out, and even through the nb, many miata owners would run 13's on their vehicles for autocross and track. In the rest of the world the twins come with 16's, and lots of rally subarus run 15's.

It is always beneficial to bring up different ideas and whether or not they are still valid for the application of the vehicles people are using.

Originally Posted by RayRay88

Please don’t put words in my mouth because you lack reading comprehension.
I suggest you re-read all my posts. Especially my last. No where did I say that you should slap on 305’s on a stock twin and you’ll turn better lap times. Does the 305 provide more lateral grip? Absolutely. Hell if you have a twin capable making use of 305’s on the track then hats off.

I was merely trying to clarify why wider tires are better on a road course. But along with every statement I qualified it with all things being equal and that there is a point of diminishing returns on each individual vehicle/setup.

The fact that you feel you need to insult just proves you don't know what you are saying. You should see ZDan's post, I have a feeling he is saying what you wish to say, but actually can write.

I wouldn't dare go anywhere near that vacuous sack of air you pretend is a functioning brain. I would fear for my life that I would catch your complete and total ineptness at communication in all its forms. The drivel you call writing wouldn't pass muster from a 6 year old, nevermind an actual intelligent adult trying to have a conversation.

Originally Posted by fatoni

My confusion comes from The fact that he's using this to make a case for a smaller wheel and tire and that's the part that is confusing me.

A smaller, lighter wheel and tire does not necessarily mean a smaller contact patch or less grip. It does mean the suspension has to do less to keep the smaller mass of the wheel and tire where it wants, and that the engine can use its power and torque more efficiently and to greater effect. It is the same reason NA and NB maita's use to run 13" wheels and tires.

Originally Posted by ZDan

All else equal, within a reasonable range, wider tires will generally give more lateral grip for reasons of contact patch shape, how it deforms under lateral load, and how that affects grip vs. load curve. Additional grip *by itself* would make you faster. The only question is where is the point of diminishing returns vs. heavier wheels/tires, aero drag, and rolling resistance. Here's what I think:

Additional aero drag from wider tires is going to be pretty damn small. Difference in vehicle frontal area with 245s vs. 215s at stock ride height is about +0.005 or one half of 1%, nothing. Coefficient of drag will be slightly different as well, but considering that the 245s will put the outside surfaces of the wheel/tire closer to the profile of the body it's possible that wider wheels/tires on stockish wheel offsets might actually reduce Cd, but either way it's going to be a small difference within a reasonable range of widths.

Rolling resistance is theoretically *less* with wider tires, as a wider/shorter contact patch undergoes less hysteresis. Tires with a narrower/longer contact patch have to have more deformation in the middle of the tread and hence lose more energy while rolling. On the other hand, wider tires with a greater mass of rubber being deformed could tilt the advantage in the other direction... In practice for a reasonable range of tire widths this effect is going to also be very small.

Additional rolling resistance due to *adhesion* (sticky rubber not wanting to let go of tarmac) is not really going to be a factor on the street on street-compound tires as in those conditions the tires don't get hot and sticky. At the track it could be a factor in lap times for low power/weight cars like the FT86 and Miata, but due to the nature of how the tire deforms I'm not sure it wouldn't be *worse* for narrower tires vs. wider. The narrower tire with longer contact patch is having to be "unpeeled" from the ground over a longer circumferential distance vs. wider tire with shorter contact patch.

The biggie in terms of how going too wide on wheels/tires can hurt you in terms of performance has got to be WEIGHT. More rotational mass will hurt acceleration of a modest power/weight car, and at some point this will hurt lap times more than increased lateral grip from wider tires helps.

In reality *other factors* have a MUCH greater impact on performance, to the point that it's difficult to isolate the effects of *only* going wider on wheels/tires without changing tire diameter and/or the stretch/pooch of the tire on the wheel (inherently an issue as tire widths are in 10mm millimeter increments and wheel widths are in 1/2" increments!).

I'm on the verge of deciding between running 225/45-17 on 17x8 or 245/40-17 on 17x9 for track events this year, and honestly I doubt that there's more than a tenth or two difference, all else equal. But I might go 245s based on vanity...

My 0.02, FWIW...

well said