Rode in a 426hp 4th gen camaro

[RdstrBlk]

The PO who was tracking my car for 13 years was using 215/45/13s on a 6" wide wheel. Way too much flex for my taste, but great grip. I switched to the larger wheel width, narrower tire width, and am getting a much better balance for my driving style (rwd bias). I can snap the rear end loose easier with trailing throttle oversteer. I can tell you that i would be outright terrified to be in the car on 165s unless it was on the track.

Maybe I'm still on the "wider is better" bandwagon, but I'm fitting tires sized appropriately for the wheel width and am not stretching. I have very little racecar experience, but a ton of trackrat time. Not basing my decisions on F1 screenings, but rather on seat time and driving experience. And a g tech sensor, so there is some data to backup my claims.

Advanced has certainly REwritten the suspension bible around here, so I'm very excited to try some narrower width wheels and tires. I can imagine the tossability goes up, lateral grip goes down. Track timea go ???

Thanks and sorry for threadjacking

[likeJIF]

Good read, thanks.

[ryanprins13]

The PO who was tracking my car for 13 years was using 215/45/13s on a 6" wide wheel. Way too much flex for my taste, but great grip. I switched to the larger wheel width, narrower tire width, and am getting a much better balance for my driving style (rwd bias). I can snap the rear end loose easier with trailing throttle oversteer. I can tell you that i would be outright terrified to be in the car on 165s unless it was on the track.

Maybe I'm still on the "wider is better" bandwagon, but I'm fitting tires sized appropriately for the wheel width and am not stretching. I have very little racecar experience, but a ton of trackrat time. Not basing my decisions on F1 screenings, but rather on seat time and driving experience. And a g tech sensor, so there is some data to backup my claims.

Advanced has certainly REwritten the suspension bible around here, so I'm very excited to try some narrower width wheels and tires. I can imagine the tossability goes up, lateral grip goes down. Track timea go ???

Thanks and sorry for threadjacking

It sounds a little like your comparing slicks to street tires but im not quite sure. What kind of tires are you talking about? A 185 wide tire thats super soft will have better grip than a 400 treadwear 165.
And you drive how your comefortable, changing your driving technique makes you slower for a while, but driving a fwd car like a rwd car is not as fast as the 'proper' technique for fwd racing.
Anyhow, with tires as small as ours there are few options so you go with the best you can get.
But if you had the same tire manufacturer making the same kind of tire out of the same compounds and they were the same circumference but one was 165 and the other was 200 width i would bet money that the 165 would give you better traction.
Maybe 175 or even 185 is optimum, but who knows, we dont have apples to apples comparisons we can do because of our less common tire diameter.
And for that matter haveing the same tire on one rim thats too narrow will have a lot different handling than that same tire on a rim thats too wide or nicely sized.
Anyway, sounds like you get to race, thats awesome you said you would be terrified to drive the car on the street with 165's, why is that? A lot of us use 145's and drive like hooligans, lol....

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[mikemounlio]

I drove my 165 hard on the street. I didnt mess around trying dumb stuff tho. Well i did hit an off ramp or two at speed but thats it. I try to stay safe. My 165 400 tread was plenty for my b6t car with a crap torque curve (all or nothing). That said i didnt get crazy on the street. Im saving it all for autocross.

[mikemounlio]

Soon i will be able to compare my current tire to my federal 595 260 tread tires. I will have lots of feedback for you guys in due time. For me its more about what i can get my hands on rather then whats best.

The econo tires are a great dialy tire. I have them on lucifer and would buy another set. If the federal 595 ends up being good ill stick to them tho. I would rather pay a bit more for a stickier tire! As far as race tire goes i may look into a full on set of federal race tires if i dont like the 595. But thats a long way away.

[RdstrBlk]

Still just comparing tire sizes, not compounds. That's another debate entirely. And r compounds are too expensive for street use (and hell even for uncompetitive track use), so we can assume 200-400 treadwear (although a huge diff still). I do understand that 20" wide tires would (if it could spin the thing) provide little traction because of little weight per area of tire. But on the flipside, 1" bike tires aint gonna have much grip even with all of that weight. Yes, contact patch is the critical factor we have identified. I'm still going to need some convincing or some data that shows the optimal tire size for the weight of the car and available power. I come from a fairly balanced roadster, so equal tire sizes and widths makes sense. Maybe with our front heavy hatches, the gains of having matched tires are lost?

But just comparing the weight over each axle of the miata, and compare it to the front axle weight of the festiva, i would say 145s are gonna spin like mad. I think a lot of this debate does boil down to tire availability, as well as consistency between brands. I've driven 200 wear rate that gripped less than 340 wear rate. I still think 165 is way too narrow, especially for the boosted folks around here. I thought the tires I put on would be too much tire, not enough tossability, but I was wrong. The tires are absolute shit. 340 wear rating chinese brand. Compared to the 140 wear rating sumitomos they feel slippery, but by removing the tire flex I'm getting a more responsive turn in, and the 2" increase in rim width also helped bring the tire to its full potential. There is a balance between tire meat and tire stretch.

Again... sorry for threadjacking.

I'm excited to hear your impressions of the federal tires, they are good for their cost IMO

[mikemounlio]

I want the federals to work due to the size/treadwear/price. If they are half as good as they look they will be my tire of choice. Not much out there for us to pick from.

[FestYboy]

Please understand that tread wear numbers are specific to the manufacturer, so a 200 for one might equal a 400 or 450 for another. That would explain the disparity you've experienced.

[ryanprins13]

Still just comparing tire sizes, not compounds. That's another debate entirely. And r compounds are too expensive for street use (and hell even for uncompetitive track use), so we can assume 200-400 treadwear (although a huge diff still). I do understand that 20" wide tires would (if it could spin the thing) provide little traction because of little weight per area of tire. But on the flipside, 1" bike tires aint gonna have much grip even with all of that weight. Yes, contact patch is the critical factor we have identified. I'm still going to need some convincing or some data that shows the optimal tire size for the weight of the car and available power. I come from a fairly balanced roadster, so equal tire sizes and widths makes sense. Maybe with our front heavy hatches, the gains of having matched tires are lost?

But just comparing the weight over each axle of the miata, and compare it to the front axle weight of the festiva, i would say 145s are gonna spin like mad. I think a lot of this debate does boil down to tire availability, as well as consistency between brands. I've driven 200 wear rate that gripped less than 340 wear rate. I still think 165 is way too narrow, especially for the boosted folks around here. I thought the tires I put on would be too much tire, not enough tossability, but I was wrong. The tires are absolute shit. 340 wear rating chinese brand. Compared to the 140 wear rating sumitomos they feel slippery, but by removing the tire flex I'm getting a more responsive turn in, and the 2" increase in rim width also helped bring the tire to its full potential. There is a balance between tire meat and tire stretch.

Again... sorry for threadjacking.

I'm excited to hear your impressions of the federal tires, they are good for their cost IMO

Post number 12 and 13 in here we talked about contact patch pressure, i dont know what the optimal psi is but it would be like a bell curve. With optimal contact patch pressure giving you the highest traction and less pressure/more pressure gives you less traction most likely on a curve.
145's are too skinny but they are usually hard rubber and tall sidewall. Mine are 600 treadware rating, lol. I think a sticky set of 145's on 14in rims on the rear would be interesting to experiment with.

And yes, the treadware rating is useless as a comparison tool across brands.

With rear wheel drive, even well balanced ones like a miata you still get a lot of weight transfer. The more power you make the more weight gets transferred to the rear wheels' contact patch and the more power you make the faster you accelerate and force=massXacceleration.
So the more power you make the wider your tires need to be to keep your contact patch pressure from getting too high.
With fwd, stock everything, when you accelerate you transfer a bit of weight off the front tires. Moving the engine foreward transferrs the engine and trans weight to the front tires making a huge improvement but the load of the firewall, dash and driver transferrs off the front to the rear tires.
So you want narrower tires on a fwd car than a rwd car of the same weight and power.

Rears of our cars should probably use narrower tires than the fronts for optimal traction but having 4 of the same is much easier and there arent much options for quality tires narrower than 165



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[Advancedynamix]

Still just comparing tire sizes, not compounds. That's another debate entirely. And r compounds are too expensive for street use (and hell even for uncompetitive track use), so we can assume 200-400 treadwear (although a huge diff still).

I run 100 tread wear tires on my grocery getter. It's very very common to see R compound rubber on street cars in my area.




These tires are actually a good bit cheaper than the Pilot super sports that came on this thing. I chew through Michelins like the value menu at Taco Bell.
Funny thing is though, Pedro sticks better on 165mm Chinese bargain rubber than my Cayman on NT01s.

I do understand that 20" wide tires would (if it could spin the thing) provide little traction because of little weight per area of tire. But on the flipside, 1" bike tires aint gonna have much grip even with all of that weight. Yes, contact patch is the critical factor we have identified. I'm still going to need some convincing or some data that shows the optimal tire size for the weight of the car and available power. I come from a fairly balanced roadster, so equal tire sizes and widths makes sense. Maybe with our front heavy hatches, the gains of having matched tires are lost?

If you could come up with a tire material to withstand a 1" wide tires, you'd be very surprised at how well it grips.
Your also correct with your assumption of different tire widths being optimal for the different ends of the vehicle, but that's nothing new or ground breaking. If you had an AWD vehicle with 50/50 weight distribution then it would be optimal to have the same width tire on all 4 corners, otherwise it's best to have the proper width for the load the tire will experience during its intended use. We stagger tires on our LeMons race car for longevity and traction reasons.

But just comparing the weight over each axle of the miata, and compare it to the front axle weight of the festiva, i would say 145s are gonna spin like mad. I think a lot of this debate does boil down to tire availability, as well as consistency between brands. I've driven 200 wear rate that gripped less than 340 wear rate. I still think 165 is way too narrow, especially for the boosted folks around here. I thought the tires I put on would be too much tire, not enough tossability, but I was wrong. The tires are absolute shit. 340 wear rating chinese brand. Compared to the 140 wear rating sumitomos they feel slippery, but by removing the tire flex I'm getting a more responsive turn in, and the 2" increase in rim width also helped bring the tire to its full potential. There is a balance between tire meat and tire stretch.

Again... sorry for threadjacking.

I'm excited to hear your impressions of the federal tires, they are good for their cost IMO

How many boosted Festivas have you driven on 165mm tires?

This was sent to me by the current owner of my last turbo festiva a few months ago. He and his wife took the car on a vacation up into the mountains to play in the snow. He and his wife regularly drive the car in the rain. At 180ft.lbs to the wheels, the 165mm tires grip way better than the 185mm tires he used to run on his B3 car (until he drove Tweak for the first time and switched to 165mm).
If that's not hard evidence, nothing is.
My b6d swapped car pulls pretty hard (all who have driven or ridden in it compare it to a healthy BP swapped festiva) yet it hooks up great with the 165/55-14 Achilles tires that I run on it. I've tracked it a bunch of times on these tires too, as well as driven through Hurricane Joaquin and even a snow storm. I've got a very healthy collection of wheels and tires, but I prefer 165mm tires for street and light track work, regardless of HP.
For heavy track work, I use wider tires. However, the compound of the tire needs to be appropriate to the width. From my own personal experience, 185mm is the best width for traction in a tire from 80 to 200 tread wear on the Festivas that I've track driven. I've run 8" wide Hoosier R35A tires and my lap times were a couple seconds slower than the 185/60-13 A048r tires that are now my go to.

[RdstrBlk]

Awesome! Was waiting for you to chime in! Okay I'm genuinely curious so I'll get some tires mounted on my 13x6 aero wheels and compare track times and g sensor data to the 15x8 wheels. I should know what to expect based on this thread, but I am still genuinely curious.

I love the deltawing, and the groundbreaking theory behind it. I know we are throwing around a lot of well defined info, but some of this is purely speculatory as we are trying to redefine the festiva. You have written the bible so far, but it isn't complete and I'm sure you would agree.

Just looking for data points as proof of theory. I'll do my testing with the stock b3 and my setup, and can give actual data based around that. Eventually I'd like to swap in a BP as it is the same motor I have been standalone tuning for 3 years, am getting 145whp on 93 pump gas. At that point I can give data from that power point.

I've never ridden in a boosted festiva, and I'm new to the car and crowd as well as fwd in general. So.. I have a lot to learn, and unlearn! Always up for a good debate, and love entertaining new concepts ans ideas. I think as a community we are right on track. I'd love to send you some photos of my suspension setup to get your thoughts. A friend of mine who also makes custom racing suspension setups looked disgusted at the amount of weight in front of the front axle. A national level competitor as yourself. The counterintuitive aspects of this car are what fuel my love for it!

[bhazard]

Don't forget the poly control arm bushings with the sticky tires

[RdstrBlk]

Ahh... just to throw another wrench in the gears!!

Taken from an autocross forum.

I imagine it has something to do with the shape of the patch, too. Given the same psi, the contact patch is going to be the exact same # of square inches regardless of the dimension of the tire, but the shape will be different for wider tires. 30 psi supporting 1/4 of a 2900lb car is 24 square inches per tire, regardless of what wheel/tire combo you're using. It's very simple physics. Which could be a 6x4" patch on a 6" wide tire, or a 12x2" patch on a 12" performance tire. My physics textbook would say both of these give the exact same friction, but there's obviously something fancier involved, as the 12" tires are well known to give much more responsive handling and stability in the corner than 6" tires. Is it that the wider tires are closer to cylindrical, and don't have to deform as much, allowing them to be stiffer with less flex, and better able to transfer those forces to the ground?

EDIT:

Adding another quote

Probably the best, short explanation is from Paul Haney's book "Racing & High Performance Tire" (available on-line at his website for $55 shipped.

"For the same vertical load and internal pressure, a tire with a wider tread has a shorter, wider contact patch than a narrower tire. The area of both contact patches is the same if the internal pressure and the load are the same. . . A shorter contact patch at the same slip angle begins to slip at roughly the same distance from the leading edge as with a long contact patch. But the shorter contact patch has more of its length stuck to the road than the longer, narrower contact patch; and therefore a larger portion of its overall area is gripping." - Why Wider Tires Are Better, p. 101

Paul's book is excellent, although it requires more serious study than most would like to give. I highly recommend it! :Checkers:

Just a little bit of backup for my claims / skepticism. I'm still legitimately interested in testing my experiment between tires, so I think I'll still give it a shot.

[mikemounlio]

OMG this topic is crazy. Try the tire you want and come to your own conclusion. I listen to what charlie says because he has lots of seat time in the car (the same kinda car). I will make my mind up as to what tire is best for me and my situation but i will start off with what he has suggested or i will get as close as i can to that.

Sometimes at the end of the day it all comes down to what works best! the math does not always paint a perfect picture.

[Advancedynamix]

The above statements are true if a vehicle never rolls and both size tires are inflated to the same pressure and have identical compositions and structures. If you plan to drive your car, that thoery may not be the answer for you. Also, wider street tires are constructed for heavier vehicles and therefor have a more rigid carcass. Our little 1800lb wonders of engineering don't weigh enough to effectively utilize the stiffer carcassed tire and this results in a lack of necessary deflection.
Wider tires do offer more lateral stability, when fitted on a properly sized wheel. They also hold up better during track driving. A 185mm tire will work better than a 165mm tire on a race track, when they have come up to temperature. With a stock b3 festiva, this may not be enough of a difference to overcome the added resistance and weight. I've driven a few b3 cars on a couple different tracks, and it's like driving one of those go karts at the fair where you never have to let off the throttle, lol. There is a lot more car there than engine. Even the b6d barely works the chassis. The b6t feels about right, but it's nothing wild or exciting (which I enjoy).
When I started using R compound tires on my b6t festiva, I started with 5.5" wide wheels with 185mm tires. I soon found out that the car needed wider wheels to support the sidewalls better. These cars place a tremendous load on the outside front tire when cornering at full tilt. I tried 6" wheels, but eventually found 7" to be the best combination. A 205 50 15 does make a great tire (with the right body mods to fit it) for a budget concious driver, as they hold up wayyyyy better than the 185/60-13 tires. That's why we run them on the front of our LeMons car. We can use that car for some back to back data on a Festiva. My findings have been a result of me taking the time to get out on the track with whatever I had available at the time. Since I never really intended on writing much about this stuff, we didn't record much of what we discovered. I just took a mental note and said, "buy another set of those" or "that didn't work". Lol