Jump to content

2015 Proposed Tire Rules (TTB-TTF)


Greg G.

Recommended Posts

I think the points look good and seem in line with the real world performance. Kudos.

 

Says the guy who just obliterated the VIR track record for TTE by ~2.7 seconds on NT-01's

Link to post
Share on other sites
  • Replies 114
  • Created
  • Last Reply

Top Posters In This Topic

  • circuitmstr

    9

  • kbrew8991

    8

  • Greg G.

    8

  • ken o

    8

scoobyej20

Is it safe to assume the R7 will be +10 and what is the time frame for this to be finalized? I need to cash in a contingency and want to try them. I assume others are in the same boat. Thanks.

Link to post
Share on other sites
  • National Staff
Is it safe to assume the R7 will be +10 and what is the time frame for this to be finalized? I need to cash in a contingency and want to try them. I assume others are in the same boat. Thanks.

Yes, like I said, that is the one item that is as close to 100% as possible. There are many that need to decide within 30 days, not just you. So, I would decide based on this statement.

Link to post
Share on other sites
circuitmstr
Greg- the new point assessment is what it is. I'm perfectly OK with it because everyone has to use the same points, BUT with the deletion of the -40mm -10pts rule, it no longer makes the new tire points assessment "fair" across the field in my opinion because it really limits lower weight/ lower HP cars to have to run wider tire sizes that are overkill for the weight that the lighter cars run at. Basically it feels as though the lighter lower HP cars

take a double hit with the new points AND also the deletion of -40mm, whereas heavier cars would only feel the points hit just like everyone else.

 

There's also a different ratio that cannot be ignored that comes in the form of : Competition weight to tread width ratio. Take a look at those ratios between heavier cars and lighter cars and it'll become apparent the perception of being penalized.

 

If one has to take points on going wider than why can't one receive the same points for going more narrow?

 

This is coming from someone that has seen things from both sides of the spectrum. I've used 275 tires for the most part on a 2770lb car and have taken the appropriate points for them, but really feel I'm in a jam if i wanted to go more narrow, so I feel I'm not biased here.

 

Just my thoughts to consider.

 

Well, its simpler than that. The heavier cars running regular sized tires are not penalized at all. The only cars penalized are the lightweight cars running skinny tires in D or above. As it sits, we handle better and they are faster on the straights. This rule brings the heavier cars closer to our handling spectrum and they stay much faster on the straights...

Greg Hates miatas...

just kidding Greg!

 

But I would like to know the thought process behind that particular rule

Link to post
Share on other sites
Show me the data showing a TTD Miata faster in any corner then a Well driven TT3 car.

 

 

Fixed it for you. And all Miaters should get an extra *

 

Peter

Link to post
Share on other sites
Greg- the new point assessment is what it is. I'm perfectly OK with it because everyone has to use the same points, BUT with the deletion of the -40mm -10pts rule, it no longer makes the new tire points assessment "fair" across the field in my opinion because it really limits lower weight/ lower HP cars to have to run wider tire sizes that are overkill for the weight that the lighter cars run at. Basically it feels as though the lighter lower HP cars

take a double hit with the new points AND also the deletion of -40mm, whereas heavier cars would only feel the points hit just like everyone else.

 

There's also a different ratio that cannot be ignored that comes in the form of : Competition weight to tread width ratio. Take a look at those ratios between heavier cars and lighter cars and it'll become apparent the perception of being penalized.

 

If one has to take points on going wider than why can't one receive the same points for going more narrow?

 

This is coming from someone that has seen things from both sides of the spectrum. I've used 275 tires for the most part on a 2770lb car and have taken the appropriate points for them, but really feel I'm in a jam if i wanted to go more narrow, so I feel I'm not biased here.

 

Just my thoughts to consider.

 

Well, its simpler than that. The heavier cars running regular sized tires are not penalized at all. The only cars penalized are the lightweight cars running skinny tires in D or above. As it sits, we handle better and they are faster on the straights. This rule brings the heavier cars closer to our handling spectrum and they stay much faster on the straights...

Greg Hates miatas...

just kidding Greg!

 

But I would like to know the thought process behind that particular rule

 

I agree. This new restriction in tire size REALLY hurts us in the lower classes! The reason it's soooo important, we have NOTHING to compensate with. Our weight is able to run on these smaller tires. If you take this away, you take away our ability to have an equalizer.

 

Drew

Link to post
Share on other sites
speedengineer

So, I submitted a rules suggestion a while back. Doubt it will go anywhere, but I am posting it here, as it would affect how base tires widths are determined, thus is relevant when discussing proposed 2015 tire rules. Perhaps it will stimulate some interesting discussion SPOILER, it involves setting base tire width on base weight, not class. But read the whole thing.

 

I believe it would remedy many of the issues I've heard B-F drivers mention over the years:

a) My 3xxxlb heavy car doesn't corner as well as those light cars, I have the same base tire size as them but weigh so much more, my tires just don't grip, and overheat quickly. How am I supposed to be competitive like this?

b) My lightweight low hp car can't compete against heavy high power cars on the straight at fast tracks, just can't keep up. Even though I'm faster in the corners, how am I supposed to be competitive against them like this?

 

Heavy cars don't get their laptime the same way as light cars. They have higher top speed because drag affects them less, but they are slower in the corners due to limited tire size. The goal of the rules to to make the cars equal in laptime. It currently doesn't (but I think it should) also have the goal of making cars equal in laptime at all types of tracks, both twisty and drag-strip like.

 

 

The Current Method:

Heavy cars don't corner as well as light cars. To help equalize laptime, they get a class weight-to-power ratio modifier (Appendix B) to make them faster yet on the straights. On 'an average' race track, this likely works very well, balancing the deficiency in the corners.

 

The Problem:

The above method skews to favor heavy cars at high speed tracks, and skews to lightweight cars favor at twisty tracks. The reason comes down to physics, namely drag-to-power ratio. A heavy car and a light car of similar size have similar drag, but with constant weight-to-power ratio, the heavy car will out accelerate the light car, because the (whp - drag_hp)-to-weight ratio is significantly higher. Even though heavy cars already accelerate better, they also get that weight-to-power modification factor that further aids their acceleration. An example, at Road Atlanta, we're talking 10-13 car lengths on the back straight between a 2400lb car and a 2800lb car, both prepped to the limit of their power to weight, as measured on dyno that weekend.

 

The Goal:

Find a way to make both heavy and light cars perform equally, regardless of the type of track. They should have similar acceleration rates, and similar cornering capability. Competition would be so much closer, and much more fun!

 

A Proposed Solution:

1) Instead of the modification factor allowing for heavy cars to have more hp, it should be opposite, allowing them to have less hp. This will equalize the acceleration rate of all of the cars in a given class.

2) Now the heavy cars need to go faster in the turns (because we just took their speed away). The best way that I can think to do this is with tire size. For example, it's not fair to ask a 3000lb TTE car to run the same skinny tires that a 2400lb miata runs. Instead of setting base tire size off of run class, we should set it using base weight. This allows that 3000lb car to run the ~255mm tires it deserves, and increases it's cornering potential to that of the lightweight car. Now BOTH cars have similar acceleration and cornering speeds. And this should hold true at most all tracks, regardless of how long of a back straight they have!

 

 

I have no idea what everyone will think about this suggestion. IF Greg wanted to consider it, the base tire size table would have to be considered here for 2015 tire rules, which is why I'm posting it here now. Thoughts?

Link to post
Share on other sites
Show me the data showing a TTD Miata faster in any corner then a TT3 car.

 

Relevance?

 

Your argument earlier on Miatas faster in corners.

Link to post
Share on other sites

Jason,

 

As someone with one of those "heavy" cars, I like your proposal. Getting tires sized correctly for the weight would be great, even if thats at the expense of some horsepower. I think your idea could work out great, it would require a bit more rule modification, but im in favor.

Link to post
Share on other sites
circuitmstr
Show me the data showing a TTD Miata faster in any corner then a TT3 car.

 

Relevance?

 

Your argument earlier on Miatas faster in corners.

 

Well I obviously would'nt be comparing a D car to anything other than another D car... lol

Link to post
Share on other sites
Jason,

 

As someone with one of those "heavy" cars, I like your proposal. Getting tires sized correctly for the weight would be great, even if thats at the expense of some horsepower. I think your idea could work out great, it would require a bit more rule modification, but im in favor.

 

+1

Link to post
Share on other sites
circuitmstr

I have discussed this with Jason. I understand the principal.

However, in my opinion it will not work.

Just as in every non spec series EVER, there will always be cars that have strengths that suit different tracks. Obviously, pro racing series deal with the same things. Inevitably, the heavier/higher hp cars will be faster on some tracks and vice versa. Nothing is going to change that.

With Jasons proposed rules the heavier cars will still be faster on the straights, albeit not as much, they will still be faster. Removing or reversing the adjustment factor for weight would not be removing substantial amounts of power. And then they get wider tires to help bridge the gap in the corners. Ugh..

I dont think the rules are that far off to make that sort of adjustment.

In my opinion the Adjustment factor for weight (that allows heavier cars more power) should go away and thats it. It wouldnt help a whole lot. But what it does is allow either advantage to be even.

There is no reason to allow them more power just because they are heavier and will inherently not handle as good. That weight penalty comes with the hidden advantage of being faster on the straights. Thats more than enough.

 

A guy with a civic beat my track record at Sebring this past weekend by 1.4 seconds in his first weekend running D with the Car. Brand new setup.

I compared the data. I am Braking at least 100ft later than him for nearly all corners, my apex speeds are 8-10mph higher in nearly every corner, yet he is still 8-10mph faster than me on every straight. and he is generally up to a speed faster than i was going within a few hundred feet of the corner exit. haha hmmm.

and he is on 225s so he will not take a penalty next year. Whereas I will not have points for a6's anymore( if the -40/-10 deal goes through). I will have to run a harder compound obviously.

even if I could run the same laptime as him. Theres no way I could compete in a race situation. cant pass someone that will drive right back around you on the straight.

Link to post
Share on other sites

the -40mm/-10 rule going away not only hurts smaller/lighter cars for the reasons previously posted. It also hurts a lot of competitors in the wallet, a smaller tire is a cheaper tire. Anything that can keep the costs under control will keep competitors on track.

Link to post
Share on other sites
Sterling Doc

I like the engineers idea, and it may be a good direction to go, though it would take a lot of testing to see what level of adjustment balances the performance HP to tire size. About the time 1/2 the people are saying it's too much, and the other 1/2 are saying it's too little, would be about right. This would also cause many to rebuild/retune, which needs to be considered as well.

 

--------------------

 

As far as data interpretation, be careful how much you extrapolate one experience to a rules recommendation. A car going 8-10 MPH would have to brake earlier, and may still be going the same speed you are when you hit the brake later. Also, late braking may be sacrificing corner entry for corner exit, which may explain some of the speed differential down the next straight. Getting on the gas earlier looks a lot like extra HP , as the distaance keeps multiplying down the straight.

Link to post
Share on other sites
speedengineer
I like the engineers idea, and it may be a good direction to go, though it would take a lot of testing to see what level of adjustment balances the performance HP to tire size. About the time 1/2 the people are saying it's too much, and the other 1/2 are saying it's too little, would be about right. This would also cause many to rebuild/retune, which needs to be considered as well.

 

--------------------

 

As far as data interpretation, be careful how much you extrapolate one experience to a rules recommendation. A car going 8-10 MPH would have to brake earlier, and may still be going the same speed you are when you hit the brake later. Also, late braking may be sacrificing corner entry for corner exit, which may explain some of the speed differential down the next straight. Getting on the gas earlier looks a lot like extra HP , as the distaance keeps multiplying down the straight.

 

Thanks Eric. It would certainly require some careful thought and some testing to get right. I actually have the means to accurately simulate the acceleration part, so we could easily determine the required modification factor to match acceleration between cars. The more difficult part would be determining how much additional tire size is required to balance the cornering speed. This would likely require some real-world testing. It's certainly doable though.

Link to post
Share on other sites
speedengineer
Get a Viper and a Lotus on track together, and let me drive them - we'll figure it out

 

Only if I get to drive too! Alright, who's got some cars to volunteer?

Link to post
Share on other sites
  • 3 weeks later...

thought of 2 good tie-breaker options it would be cool to see added. The first 6 are fine, for a 7th one consider adding number of track records driver A has vs driver B. 8th one consider looking at time differential in the head-to-head matchups (IE Driver A won by 0.100 and 0.250 in two of the HTH matchups, but Driver B won by 1.250 and 0.500 in two of the other HTH matchups = Driver B wins). Or reverse their order desired (7th one combined MOV, 8th one TRs instead).

 

Yeah yeah I know it's rare to go past tiebreaker 3 or 4, but that doesn't mean we can't add a couple more to really ensure there's almost no possible way to tie.

Link to post
Share on other sites
  • 3 weeks later...

I suggest the following based on my observations:

 

1) The following DOT-approved R-compound tires: BFG R1S, Goodyear Eagle RS AC (autocross), Hankook Z214 (C90 & C91 compound only), Hoosier A7, Hoosier Wet DOT (if used in dry conditions—see section 5.6) +17

2) The following DOT-approved R-compound tires: Hoosier A6 +15

3) The following DOT-approved R-compound tires: BFG R1, Hoosier R7 & SM7 +13

4) The following DOT-approved R-compound tires and those with a UTQG treadwear rating of 40 or less not listed otherwise in these rules: Goodyear Eagle RS, R6 & SM6, Hankook Z214 (C71, C70, C51, C50), , Kumho V710 (note: Continental Tire Sportscar Challenge EC-Dry tires OK (225, 245, 275) +10

 

I also just want to know what the final decision is so I can be ready for our first race which is only 7 weeks away!!

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...