Jump to content
ianacole

Slick vs. DOT usage

What tire do you run?  

60 members have voted

  1. 1. What tire do you run?

    • Slick
      16
    • D.O.T.
      44


Recommended Posts

mater

I run 16' wheels and can only fit slicks on my e30.So I could benefit>>>> but my car is 22 years old too!!! SOOOO lets change it so I can get more hp to push my e30 brick through the air.

Share this post


Link to post
Share on other sites
ELEPHANT1
Now this is an interesting thread. My initial thinking was that age old "slicks are faster than DOTs" but I am well aware that gap is not as big as it used to be. And honestly, I could not come up with one valid argument for having classes split based on tires as a single component choice. Though I think it would be detrimental to me personally, I think I'd rather see tires not be a defining factor of classing. Very interesting.

 

Cheers.

 

Ok, there is one argument - and I'm not saying I agree with it or even that it's a good one - to keep separate ratios based on tires....the majority of cross over cars (both existing and potential) run DOT's in the other series.

 

But the more I think about it I really don't like singling out tires as a specific component that alters classing. I say do away with that.

 

Cheers.

Share this post


Link to post
Share on other sites
mater

I agree with you tires should not alter a class. I have to run 16' wheels too lower my car in order to get a decent neg. camber #

Share this post


Link to post
Share on other sites
B.Watts
Ok, there is one argument - and I'm not saying I agree with it or even that it's a good one - to keep separate ratios based on tires....the majority of cross over cars (both existing and potential) run DOT's in the other series.

 

I understand how that argument could be made in the present while GTS is mostly just another place for BMW and Porsche club racers to race their cars...but that's a dangerous argument. None of the crossover cars are allowed a sucker fan and full underbody to hold the car down on the pavement. So when someone shows up with such a setup in GTS, are we going to create a new sucker fan class? Similar arguments could be made about a $40K set of quad adjustable dampers or any of the modifications that are allowed in GTS that aren't allowed in many of the classes that cars are currently crossing over from.

 

If we must seperate cars with slicks out, then they should be in separate class. GTS-3 DOT and GTS-3 Non-DOT. That seems to make more sense to me than placing the cars in classes together using some arbitrary guess as to how much weight/hp benefit makes up the difference in performance between the two kinds of tires. And since Toyos aren't competitive with Hoosiers, we should probably give the Toyo guys a weight break in the DOT classes, right?

 

And since it doesn't really make sense to make separate classes for DOT Hoosier, DOT Toyo, and Non-DOT, let's just let everyone play by the same rules and lump everyone together without any penalty for running a specific kind of racing tire.

Share this post


Link to post
Share on other sites
ELEPHANT1
Ok, there is one argument - and I'm not saying I agree with it or even that it's a good one - to keep separate ratios based on tires....the majority of cross over cars (both existing and potential) run DOT's in the other series.

 

I understand how that argument could be made in the present while GTS is mostly just another place for BMW and Porsche club racers to race their cars...but that's a dangerous argument. None of the crossover cars are allowed a sucker fan and full underbody to hold the car down on the pavement. So when someone shows up with such a setup in GTS, are we going to create a new sucker fan class? Similar arguments could be made about a $40K set of quad adjustable dampers or any of the modifications that are allowed in GTS that aren't allowed in many of the classes that cars are currently crossing over from.

 

If we must seperate cars with slicks out, then they should be in separate class. GTS-3 DOT and GTS-3 Non-DOT. That seems to make more sense to me than placing the cars in classes together using some arbitrary guess as to how much weight/hp benefit makes up the difference in performance between the two kinds of tires. And since Toyos aren't competitive with Hoosiers, we should probably give the Toyo guys a weight break in the DOT classes, right?

 

And since it doesn't really make sense to make separate classes for DOT Hoosier, DOT Toyo, and Non-DOT, let's just let everyone play by the same rules and lump everyone together without any penalty for running a specific kind of racing tire.

 

Oh I agree completely...it was just the only thing I could think of. ; ) More and more I think we should do away with tire based classification.

 

Cheers.

Share this post


Link to post
Share on other sites
ianacole

Please bear in mind that I am not arguing for or against ... I'm not quite sure how I feel yet, but someone asked about the performance differential between DOT tires and slicks, so I spoke with Jeff Speer at Hoosier, and here is the results of our conversation:

 

Given an average track of ~2.3 miles and 12ish turns, and a car properly set up to maximize the tire, and comparable sized tires, a driver can expect:

 

  • The R100 compound (newest) slick will be 2-3 seconds faster than an A6, and the A6 should be 2-3 seconds faster than the R6 (not over a full race, but in a single lap).
  • The R100 will be $80-100 more expensive than the DOT compound
  • The R100 will last ~1.5 times longer than the R6 (you'll go through 1.5~2 sets of R6s in the same time you go through 1 set of R100s). This means that the long term cost of running slicks in shear volume of tires could be more cost effective.

 

Of course, experiences may vary, as will actual results. Currently, if I understood Jeff correctly, the R100 compound is only available for 18" wheels, with 17" sizes on the horizon.

Share this post


Link to post
Share on other sites
ELEPHANT1

Yeah, sure....and it's not rules change time anyway. ; )

 

But for the record, I'm for it. ; )

 

Cheers.

 

Please bear in mind that I am not arguing for or against ... I'm not quite sure how I feel yet, but someone asked about the performance differential between DOT tires and slicks, so I spoke with Jeff Speer at Hoosier, and here is the results of our conversation:

 

Given an average track of ~2.3 miles and 12ish turns, and a car properly set up to maximize the tire, and comparable sized tires, a driver can expect:

 

  • The R100 compound (newest) slick will be 2-3 seconds faster than an A6, and the A6 should be 2-3 seconds faster than the R6 (not over a full race, but in a single lap).
  • The R100 will be $80-100 more expensive than the DOT compound
  • The R100 will last ~1.5 times longer than the R6 (you'll go through 1.5~2 sets of R6s in the same time you go through 1 set of R100s). This means that the long term cost of running slicks in shear volume of tires could be more cost effective.

 

Of course, experiences may vary, as will actual results. Currently, if I understood Jeff correctly, the R100 compound is only available for 18" wheels, with 17" sizes on the horizon.

Share this post


Link to post
Share on other sites
mater

I think Jeff "as he should"is "trying" promoting the new compound as being 2-3 sec. faster in order to sell tires.ITs always newer better and so on in conversation!!

Share this post


Link to post
Share on other sites
RSCoupe

I'm for keeping them seperate, but then, one of my competitors is running slicks, and he said he gained 2-3 seconds a lap when he switched to them.

Share this post


Link to post
Share on other sites
Michael G.

We also need to remember in comparing, that there are "other" slicks but the newest R100 out there (which are one of the most expensive ones at $400-500/tire, and presumably, one of the fastest now, comparable to Michelin's blue). Most of the drivers are still using Yoko's, Dunlops, Michelin's yellows and others, at almost half the cost (pretty much the same as DOT-Rs), and not as "fast" as the top models. I think, that in the times of the current developments in the tire technologies, we need to acknowledge that the line drawn between DOT-Rs and slicks is not as clear and well defined anymore (not in cost or benefits), especially to use it as a single major deciding factor on classing. I don't have any easy to apply formulas or solutions, but I expect us to run into more and more issues with that in the near future, unless we will start developing a comprehensive approach to the subject. Michael G. NE GTS Dir.

Share this post


Link to post
Share on other sites
claykos
Please bear in mind that I am not arguing for or against ... I'm not quite sure how I feel yet, but someone asked about the performance differential between DOT tires and slicks, so I spoke with Jeff Speer at Hoosier, and here is the results of our conversation:

 

Given an average track of ~2.3 miles and 12ish turns, and a car properly set up to maximize the tire, and comparable sized tires, a driver can expect:

 

  • The R100 compound (newest) slick will be 2-3 seconds faster than an A6, and the A6 should be 2-3 seconds faster than the R6 (not over a full race, but in a single lap).
  • The R100 will be $80-100 more expensive than the DOT compound
  • The R100 will last ~1.5 times longer than the R6 (you'll go through 1.5~2 sets of R6s in the same time you go through 1 set of R100s). This means that the long term cost of running slicks in shear volume of tires could be more cost effective.

 

Of course, experiences may vary, as will actual results. Currently, if I understood Jeff correctly, the R100 compound is only available for 18" wheels, with 17" sizes on the horizon.

 

 

This is simply an exaggeration. I have run A6s, R6s and R100s on the same car. I also have extensive experience switching between A6s and R6s on a different car. Most of my experience is on a shorter track (Phoenix Int'l Raceway roval), 1.6 miles and 10 turns. For reference, pole time for Rolex GT in 2006 or 2007 was around 1:02 or 1:03. Pole time for Grand Am GS class was around 1:08.

 

For the A6/R6/R100 comparison, the car is a 2500 lb, 350 rwhp Porsche 911. The car that I have A TON of experience on A6s and R6s in is a 2500, 240 rwhp Porsche 911.

 

On the 240 rwhp car: On R6s, in good track conditions I could run mid 1:06. On A6s, in good conditions, I could run 1:05.7.

 

On the 350 rwhp car: On R6s I could run 1:05.0. A6s 1:04.7 (but I would burn them up very quickly on the rear). On the R100/R80 slicks I have run 1:03.8. The A6, R6 comparison on this car is not entirely consistent because the tires were of a different age.

 

On tire wear: The R6s were good for ~8 runs before they fell off quite a bit. They were certainly still usable, but not as fast as new. The A6s have been pretty good up until they cord, which is usually 12-16 runs depending on conditions. I am on my first set of the slicks. They seemed to fall off really badly during my 5th run on the tires. They are still usable, but about 1 second off of stickers.

Share this post


Link to post
Share on other sites
B.Watts

Been out of town for a bit and I had forgotten about this thread.

 

This is simply an exaggeration.

 

Agreed. Hugely so. If the A6 was 2-3 seconds faster than the R6, no one would be running the R6 in a competitive class. We've already seen the A6's will last for an entire sprint race in multiple venues without any huge dropoff in laptimes...even on some heavier Showroom Stock and Touring cars at SCCA Runoffs. Why would anyone who wishes to be competitive actually run R6's? The A6's may get less heat cycles, but could you really afford to give up 2-3 seconds if you wanted to run at the front?

 

My best laptimes at VIR are mid 1:58's in our car on R100's in GTS5 trim. I "think" I'm a decent driver...slower than I was in the past, but I'm not that far off the pace. Slower classed Prepared M3's (that run as GTS3 cars with a bit of ballast) are running R6's and turning 2:04-2:06's as their flyer laptimes. According to the post above, if I put R6's on our car, our GTS5 car would be running the same laptimes as GTS3 cars that are already on R6's. Ehh, no...that's simply not the case.

 

We've asked a similar question of Hoosier. When asked if they have compared the A6 to the R6 to the R100 on the same car, the answer was "sort of" with some general number ranges thrown out there that were similar to, but slightly less optimistic than the numbers posted on this thread. If they have really been compared, we wouldn't need a range. Hoosier should be able to say that on Car XY, Tire B is 1.5 seconds faster than Tire A on Track 1234.

 

My best guess is that the R100's are about 0.8 to 1.2 seconds faster than the A6's, which are probably a 0.1-0.3 seconds faster than the R6's around a track like VIR. There's simply not a 6 second difference in fastest laptime between the R100 and the R6. We, too, have had R100's, R6's, and A6's on our car. We haven't run enough testing or done enough tweaking to have any meaningful numbers to share. But I am pretty confident in saying that no amount of tweaking to the setup is going to result in finding a 6 second gap between the R6's and R100's.

 

If Hoosier doesn't really know how much time there is between their tires, we KNOW that our rules aren't doing a good job of trying to even the playing field between the two types of tires.

 

All of this to say: Hoosier has been GREAT to work with. This isn't a knock on them in any way.

Share this post


Link to post
Share on other sites
Eric W.

Not to grind anyone's gears or anything... the PT rules make you take a +30 penalty for slicks!

 

That's pretty crazy IMO.

Share this post


Link to post
Share on other sites
philstireservice
Not to grind anyone's gears or anything... the PT rules make you take a +30 penalty for slicks!

 

That's pretty crazy IMO.

 

 

+30 is outragous......I can see +15 tops

Share this post


Link to post
Share on other sites
cstreit911

I'll 2nd and 3rd B.Watts and claykos observations.

 

I ran R6's and A6's last last year alternately on tracks I have a lot of experience on. There was not much time difference between the two. A few 10th's possibly. However the A6's came up to temp and went away quicker than the R6's. Might work for short sprints, but definitely not a viable option for me in 30+ minute races.

Share this post


Link to post
Share on other sites
krisa9977

With proper car setup, slicks much faster then any DOT tires and definitely worth +30 for PT or even more. A6 Hoosiers have very soft sidewall and overheat too fast. May be they are faster then R6, but only a few 10th's

Share this post


Link to post
Share on other sites
Eric W.

I was always under the impression the A6 and R6 had the same sidewall construction but differed in compound...

 

With proper setup, I still dont think slicks have a 20 point advantage over regular Hoosiers (+10 vs. +30).

Share this post


Link to post
Share on other sites
sstecker

so if the slick rule may be changing what about the tube frame rule?

Share this post


Link to post
Share on other sites
RSCoupe
so if the slick rule may be changing what about the tube frame rule?

 

What cars came from a manufacturer already a tube frame? None that I know of, so I would vote no to changing that rule.

Share this post


Link to post
Share on other sites
B.Watts
so if the slick rule may be changing what about the tube frame rule?

 

What cars came from a manufacturer already a tube frame? None that I know of, so I would vote no to changing that rule.

 

What cars come from the factory with 4 way adjustable $50K dampers, 10,000 RPM motors, and full race aero? All of those things are perfectly legal in the rules.

 

That said, I agree with you. In my opinion, we should get rid of full tube frames completely, requiring the passenger compartment portion of the chassis to at least remain, which would allow for "tube framing" in front of and behind the passenger compartment if desired. Just seems more in the spirit of the class to at least keep the main portion of the chassis.

Share this post


Link to post
Share on other sites
sstecker
so if the slick rule may be changing what about the tube frame rule?

 

What cars came from a manufacturer already a tube frame? None that I know of, so I would vote no to changing that rule.

 

What cars come from the factory with 4 way adjustable $50K dampers, 10,000 RPM motors, and full race aero? All of those things are perfectly legal in the rules.

 

That said, I agree with you. In my opinion, we should get rid of full tube frames completely, requiring the passenger compartment portion of the chassis to at least remain, which would allow for "tube framing" in front of and behind the passenger compartment if desired. Just seems more in the spirit of the class to at least keep the main portion of the chassis.

 

thats allowed under the non tube frame ruleset - "Modification of suspension and drivetrain mounting points alone does not constitute a tube frame." which seems counter to the intent of penalizing tube frames. its ok to move the motor back 2', goto double a arms suspension front/back, sequential trans axle as long as i keep the oem chassis.

Share this post


Link to post
Share on other sites
B.Watts
thats allowed under the non tube frame ruleset - "Modification of suspension and drivetrain mounting points alone does not constitute a tube frame." which seems counter to the intent of penalizing tube frames. its ok to move the motor back 2', goto double a arms suspension front/back, sequential trans axle as long as i keep the oem chassis.

 

It makes sense, at least to me, that any modification should be allowed as long as you keep the stock A/B/C pillars. So yes, that includes "tubing" the front and the back of the car and doing whatever you like to the suspension. Otherwise, by allowing a ground up chassis without using any of the stock chassis, I could take an ALMS Prototype car, drop in a BMW motor, and run it in GTS. That just seems outside the spirit of the rules to me since the rules are designed to give German cars a place to compete against each other. Full tube frame cars just don't seem to have any business running in GTS to me.

Share this post


Link to post
Share on other sites
scottbm3
thats allowed under the non tube frame ruleset - "Modification of suspension and drivetrain mounting points alone does not constitute a tube frame." which seems counter to the intent of penalizing tube frames. its ok to move the motor back 2', goto double a arms suspension front/back, sequential trans axle as long as i keep the oem chassis.

 

It makes sense, at least to me, that any modification should be allowed as long as you keep the stock A/B/C pillars. So yes, that includes "tubing" the front and the back of the car and doing whatever you like to the suspension. Otherwise, by allowing a ground up chassis without using any of the stock chassis, I could take an ALMS Prototype car, drop in a BMW motor, and run it in GTS. That just seems outside the spirit of the rules to me since the rules are designed to give German cars a place to compete against each other. Full tube frame cars just don't seem to have any business running in GTS to me.

 

In the 2008 rules it was as described by Bryan. Not sure why it didn't transfer over, but it should, or maybe just needs to be a bit more defined. I also think the other rules(which are few) currently in effect should be left as they are. Including DOT vs Slick and the HP/TRQ. equation. It's a simple ruleset that works well, lets keep it that way,

 

 

-Scott B.

Share this post


Link to post
Share on other sites
sstecker
thats allowed under the non tube frame ruleset - "Modification of suspension and drivetrain mounting points alone does not constitute a tube frame." which seems counter to the intent of penalizing tube frames. its ok to move the motor back 2', goto double a arms suspension front/back, sequential trans axle as long as i keep the oem chassis.

 

It makes sense, at least to me, that any modification should be allowed as long as you keep the stock A/B/C pillars. So yes, that includes "tubing" the front and the back of the car and doing whatever you like to the suspension. Otherwise, by allowing a ground up chassis without using any of the stock chassis, I could take an ALMS Prototype car, drop in a BMW motor, and run it in GTS. That just seems outside the spirit of the rules to me since the rules are designed to give German cars a place to compete against each other. Full tube frame cars just don't seem to have any business running in GTS to me.

 

agree the lmp would be outside the spirit. keeping stock a/b/c with tubes gives you basically dtm style. think they keep the centerline hood to trunk stock?

Share this post


Link to post
Share on other sites
EdNewman
Please bear in mind that I am not arguing for or against ... I'm not quite sure how I feel yet, but someone asked about the performance differential between DOT tires and slicks, so I spoke with Jeff Speer at Hoosier, and here is the results of our conversation:

 

Given an average track of ~2.3 miles and 12ish turns, and a car properly set up to maximize the tire, and comparable sized tires, a driver can expect:

 

  • The R100 compound (newest) slick will be 2-3 seconds faster than an A6, and the A6 should be 2-3 seconds faster than the R6 (not over a full race, but in a single lap).
  • The R100 will be $80-100 more expensive than the DOT compound
  • The R100 will last ~1.5 times longer than the R6 (you'll go through 1.5~2 sets of R6s in the same time you go through 1 set of R100s). This means that the long term cost of running slicks in shear volume of tires could be more cost effective.

 

Of course, experiences may vary, as will actual results. Currently, if I understood Jeff correctly, the R100 compound is only available for 18" wheels, with 17" sizes on the horizon.

 

So far, I have NOT been able to beat my personal best times on R6's with the new slicks. I think next year, I am going to get a set of A6's in the spring and run them back to back one day and see what happens.

Share this post


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...