"Autocross Tires" not allowed - How do I identify these?

[MXDave813s]

Hi Greg, my question is regarding the tires. I read the rule that "R" rated Autocross specific tires are not permitted. How do I identify these? Likely a basic question but appreciate your feedback.

Thank you!

David

 

 

Edited July 25, 2019 by MXDave813s

[Clavette]

I am not Greg but what tires are you considering?

Here's a blurb from 6.5.2 of ST 1-4 rules

DOT-approved R-comp Autocross tires
(examples: A6, A7, DOT Wet, R1S, RS AC, Z214-C90/91)

https://nasa-assets.s3.amazonaws.com/document/document/16301/ST1-4___SU_Rules__2019--v13.3--4-24-19.pdf

Edited July 25, 2019 by Clavette

[MXDave813s]

Thank you Clavette! We have been using Federal 595 RS-RRs through our HPDE journey 1 - 4. When filling out the submission form for ST/TT5, I read the rule about not allowing Autocross specific tires in ST5/6. 

[DavidSinger]

I am not reassured by these replies.

Version 2.5 of ST5/6  rules are vague as to determining how to identify "DOT-approved R-comp Autocross tires" (other than the samples listed).  For instance, if a brand model has an "R" in the product name, does that identify it conclusively as R-composition?

I currently have Federal 595 RS-RRs and Federal 595 RS-RSs mounted.  They are TW 200 and TW 240 respectively.  Their benefit is (1) they fit well, and (2) they are cheap and run reasonably well in the wet, meaning one set of tires gets me racing.  But are they "R-comp"?

 

Adding to my confusion is

6.3.2 Modification Factors  Tires: Tires with a UTQG Treadwear rating 100 or greater = +0.5

which implies that ST6 can run *any* tire compound for no mod factor, but if a TW of 100 or more tire is mounted then my car gets a +.5 mod factor.

 

What I'd *really* want to run as an affordable racing tire is Federal's FZ-201(M).  These are TW 100.

They fit perfect. I get +.5 Mod Factor.  But wait, are they "R-comp"?

Do I have to dismount my TW240 Federal 595 RS-RS tires because they are "R-comp"?

Do I have to dismount my TW200 Federal 595 RS-RR tires because they are "R-comp"?

How does a car owner figure this out when looking at a tire's sidewall or Mfg literature?

[1jeffcat]

On 10/1/2019 at 8:48 PM, DavidSinger said:

I am not reassured by these replies.

Version 2.5 of ST5/6  rules are vague as to determining how to identify "DOT-approved R-comp Autocross tires" (other than the samples listed).  For instance, if a brand model has an "R" in the product name, does that identify it conclusively as R-composition?

I currently have Federal 595 RS-RRs and Federal 595 RS-RSs mounted.  They are TW 200 and TW 240 respectively.  Their benefit is (1) they fit well, and (2) they are cheap and run reasonably well in the wet, meaning one set of tires gets me racing.  But are they "R-comp"?

 

Adding to my confusion is

6.3.2 Modification Factors  Tires: Tires with a UTQG Treadwear rating 100 or greater = +0.5

which implies that ST6 can run *any* tire compound for no mod factor, but if a TW of 100 or more tire is mounted then my car gets a +.5 mod factor.

 

What I'd *really* want to run as an affordable racing tire is Federal's FZ-201(M).  These are TW 100.

They fit perfect. I get +.5 Mod Factor.  But wait, are they "R-comp"?

Do I have to dismount my TW240 Federal 595 RS-RS tires because they are "R-comp"?

Do I have to dismount my TW200 Federal 595 RS-RR tires because they are "R-comp"?

How does a car owner figure this out when looking at a tire's sidewall or Mfg literature?

You don't have to dismount anything.  

"R-comp" is a loosely used term for DOT competition tires.  

A specific example is the Hoosier R7 and A7...both are R comps, but the A7 is an Autocross tire.  They both have the same levels of grip, but the A7 has a softer autocross compound that gets to temperature much more quickly, therefore somebody in a TT event could theorhetically have more hot laps at an optimal tire temperature, hence they are banned.  The regular Hoosier R7 takes longer to build heat, but is more durable as it dissipates heat better for track/racing scenarios for the length of a race, instead of burning up like A7s would.

So the rules are stated as any DOT tire is legal, EXCEPT for autocross compounds, such as Hoosier A7s, BFG R1S(soft), etc.

So any other DOT tire is legal including Hoosier R7, BFG R1(non-S), Toyo RR, various hankook or kuhmo non-auto X tires.  

NASA can give you a 0.5 modifier back to your advantage if you run 100tw or greater tires such as Maxxis RC1(maxxis calls them an "R-comp"), Maxxis VR1, BFG Rival S, Bridgestone RE71, any Federal 595(minus their rare full slick one that nobody uses), Hankook RS4, etc.  The Federal FZ-201 is also legal.  All of these tires are >100tw street tires whether they are desirable "autocross" tires or not.  They are nowhere near the same level of grip as the illegal 40tw Hoosier A7 or BFG R1S.  

Edited October 9, 2019 by 1jeffcat

[DavidSinger]

Thanks 1jeffcat.  I think this boils down to "If it is greater than or equal to100tw, it is not an R-Comp tire."

Edited October 10, 2019 by DavidSinger
change > to GE

[1jeffcat]

5 hours ago, DavidSinger said:

Thanks 1jeffcat.  I think this boils down to "If it is greater than or equal to100tw, it is not an R-Comp tire."

Not necessarily, but yea in most cases.  Like I said, Maxxis considers their RC1 their "R comp", but it is a 100tw tire, but for all intents and purposes, what you are stating is typically the case.  

[DavidSinger]

OK, noted.  NASANE raised TREC limits to TW180, which I would presume cannot possibly include any R-Comp. But if we were to run sprints, then TW100 would be of great interest.

[1jeffcat]

1 hour ago, DavidSinger said:

OK, noted.  NASANE raised TREC limits to TW180, which I would presume cannot possibly include any R-Comp. But if we were to run sprints, then TW100 would be of great interest.

Doesn't include any "R comp" to my knowledge, but like I said, R comp is just a vague term.  200tw RE71s are faster than 100tw Maxxis RC1s.

[Tansar_Motorsports]

To further clarify:  Without either Hoosier R7 or BFG R1, you will not be able to run competitively.  The 0.5 mod factor is not enough to make TW100+ tires competitive with the much faster DOT slick tires.

If you don't care about being competitive, then run whatever TW100+ tires you want.

[DavidSinger]

" Without either Hoosier R7 or BFG R1, you will not be able to run competitively. "

Thank you for that observation [specific tires vs mod factor]

R7 is not available to fit my car, so R1 it be for TT or sprints.

If we run any.

As I mentioned above, NASANE bumps the TW to180 for TREC, which widens the range of competitive tires into the more affordable options.

For 2020, the primary objective is to finish each TREC.  Podium would be nice, but the build is a totally new car with a lot of learning curve, including drivers not accustomed to FWD momentum driving.  We are not chasing miracles, and are reluctant to throw tires at the car.  Our philosophy is to make sure all the rest of the running gear works first, settle the areo second, then fit shoes for the growing baby.

Has a 235/40 17 BFG R1 on an 8 inch rim been tested with the 257mm template?  My guess is it would pass, but there is nothing like local knowledge to be sure.

[1jeffcat]

7 hours ago, DavidSinger said:

" Without either Hoosier R7 or BFG R1, you will not be able to run competitively. "

Thank you for that observation [specific tires vs mod factor]

R7 is not available to fit my car, so R1 it be for TT or sprints.

If we run any.

As I mentioned above, NASANE bumps the TW to180 for TREC, which widens the range of competitive tires into the more affordable options.

For 2020, the primary objective is to finish each TREC.  Podium would be nice, but the build is a totally new car with a lot of learning curve, including drivers not accustomed to FWD momentum driving.  We are not chasing miracles, and are reluctant to throw tires at the car.  Our philosophy is to make sure all the rest of the running gear works first, settle the areo second, then fit shoes for the growing baby.

Has a 235/40 17 BFG R1 on an 8 inch rim been tested with the 257mm template?  My guess is it would pass, but there is nothing like local knowledge to be sure.

It will easily fit. 

A 255/40/17 RE71 on a 17x9.5 clears the 257mm template.  

A 255/40/17 Toyo RR on a 17x9 clears the 257.  

Edited October 12, 2019 by 1jeffcat

[1jeffcat]

11 hours ago, Tansar_Motorsports said:

To further clarify:  Without either Hoosier R7 or BFG R1, you will not be able to run competitively.  The 0.5 mod factor is not enough to make TW100+ tires competitive with the much faster DOT slick tires.

If you don't care about being competitive, then run whatever TW100+ tires you want.

I'd beg to differ...especially in TT, where the operating temps get up to temp quicker with street tires compared to R7s, of which have difficulty even getting to operating temp in a 15 min TT session on SOME cars.  The problem is no competitive people try to run the proper street setup.  It's also very car specific, with years of inaccurate comparisons of 205 street tire vs 205 hoosier, which is equivalent in section width to a 225/235 street tire, and then not adjusting camber...example being some street tires need less camber than Hoosiers, which increases their braking capacity, plus a lot of street tires can be shaved to improve their contact patch and shed a lot of reciprocating weight.  Apples to oranges comparisons between the two.  Just going off a personal experience, certain 200tw, in an optimal fitment could run right with hoosiers with the 0.5 modifier.  Nobody believes me, but that's fine.  We have run enough tires on different setups in NASA and enduros to know otherwise.  

[DavidSinger]

1jeffcat, I think yiu have a valid point.  One also has to factor in offset, scrub radius, and getting the tires to not rub the suspension.  Topic is restriction on autox compounds.  Before I need to worry about *which* sticky compound, I have to find wheels that don't destroy an otherwise beautiful steering geometry.   Factory was 17x7 4x108 49mm. There are but 2 rims available in 17x8 4x108 45mm, and one of those brands is no longer made.  Before I look into sticky 255s, I have to first find 17x9 4x108 (old Cobra rims probably) with an as yet unknown offset.  Since the current 235s on the proper offset 8" rim leaves a creditcard-thin gap between sidewall and strut, moving to 255s will most likely require an offset that might widen the track width beyond the 4 inch limit, and will increase the scrub radius.  I might lose more traction than I gain, or worse fail tech.  Fortunately, working out these technical problems is part of what I enjoy in building race cars.

[1jeffcat]

11 minutes ago, DavidSinger said:

1jeffcat, I think yiu have a valid point.  One also has to factor in offset, scrub radius, and getting the tires to not rub the suspension.  Topic is restriction on autox compounds.  Before I need to worry about *which* sticky compound, I have to find wheels that don't destroy an otherwise beautiful steering geometry.   Factory was 17x7 4x108 49mm. There are but 2 rims available in 17x8 4x108 45mm, and one of those brands is no longer made.  Before I look into sticky 255s, I have to first find 17x9 4x108 (old Cobra rims probably) with an as yet unknown offset.  Since the current 235s on the proper offset 8" rim leaves a creditcard-thin gap between sidewall and strut, moving to 255s will most likely require an offset that might widen the track width beyond the 4 inch limit, and will increase the scrub radius.  I might lose more traction than I gain, or worse fail tech.  Fortunately, working out these technical problems is part of what I enjoy in building race cars.

Fair enough.  Typically mild scrub radius changes are just that, but I enjoy the attention to detail.  Mind you camber settings and wheel offset can mitigate the extra positive scrub radius.  That's something you would have to test, but at face value, I think I'd prefer the slightly positive scrub radius with a larger tire, then trim it out a bit with camber as needed(if needed).  Obviously, the negative scrub radius would fare better in inclement conditions.  Each car, setup, etc is specific to each individual application.  

[Tansar_Motorsports]

1jeffcat,

I hope you can prove people wrong.  Optimize a setup for 100+ TW, go out there, and start winning.

[DavidSinger]

Tansar_M  I am attempting that as well.  It took Ford 3 years to figure out GT, and they simply blew up engines and wrecked cars to find out what needed improvement.  My resources are a bit more limited than Ford's.  I expect it might take more than 3 three years.  Or forever.  It is the challenge, you know?

"Show" and "Go".  Great names!

Edited October 15, 2019 by DavidSinger
Added content.