Q&A With a Tire Engineer: R-Comp Race Tires vs. 200-Treadwear Extreme Street Tires

Sponsored article presented by Maxxis Tires.

 

Today’s 200-treadwear tires have gotten fast–really fast–and have become a staple in autocross, time trials and endurance racing. But don’t forget their true purpose: At the end of the day, they’re designed for the street.

How about running a true race-ready, R-comp tire in these events instead? Yes, they’re also street-legal and carry a DOT stamp, but they’re engineered more for the track than the road. That means less comfort but more speed. 

One look immediately reveals their different missions: Where the 200-treadwear tires feature some tread, R-comps practically resemble full slicks. 

We’ve tested 200-treadwear tires against R-comps before–same car, same size, same tire manufacturer–and the lap times revealed the performance advantage: 28.114-second autocross laps for the street tires and 27.703-second laps for the race tires. 

The in-car data, though, showed even bigger advantages for the race rubber: higher average g-force readings through the turns, much quicker transitions, higher throttle load capacity, and more grip in straight-line situations–meaning quicker acceleration. 

What if we could peek inside the two tires to see how the magic happens? 

We asked someone who could take us there: Meet John Wu, an engineer by training and now director of product strategy for Maxxis USA. He’s been working in the tire industry since 2005 and has been a track day participant for 20 years. 

Maxxis has one foot in each of these tire camps, too. The brand’s Victra VR-1 is a 200-treadwear model designed for today’s extreme summer tire market. It features a full tread for daily use yet is still suitable for motorsports events. A GRM tire test showed that it should do well in endurance races that require tires carrying the 200-treadwear stamp of approval.


The Maxxis Victra VR-1 is a 200-treadwear model designed for today’s extreme summer tire market.

For those looking for more speed, Maxxis offers the Victra RC-1, a 100-treadwear, R-comp model tuned for track use. It features the minimum two grooves required for DOT approval and is tuned solely for the track. Its mission statement is posted right there on the Maxxis website: Recommended for DRY COMPETITION EVENTS ONLY.

 
The Maxxis Victra RC-1 is a 100-treadwear, R-comp model tuned for track use.

GRM: What specifically makes R-comp tires faster than true street tires?
Maxxis: R-comp tires are engineered with much shallower tread depth plus a specific pattern, profile, construction and compound design for track use. 

Shallower tread depth means a shorter tread block height. Shorter tread blocks do not move or flex as much as taller tread blocks and therefore don’t generate as much heat when the tire is driven to the limit. 

The downside is you have less void for water evacuation. Therefore, most companies usually recommend R-comps for dry use only due to their limited wet-weather performance.

The pattern design will usually employ large tread blocks or continuous ribs to maximize road contact and tread block rigidity. Engineers analyze the contact patch shape–aka footprint–and optimize a tread design to work well with footprint changes under load. 

Engineers also have to make sure the tread will wear somewhat evenly under racing conditions, so this is where expertise and technology come in. 

Tire profile design is another tool we have to optimize the footprint shape for wear and performance. Typically, R-compounds will have very large-radius profile designs, whereas street tires will be more reserved. Large-radius profile designs make the tire sidewall/shoulder area look “beefy” and “square.” That larger radius gives us the footprint we want and need in an R-compound.

Most materials start to lose their strength/rigidity with heat, so our engineers pick materials that can handle the heat generated under racing conditions. Construction of R-compounds usually utilizes high-tensile-strength materials that are more resistant to heat. This tensile strength provides a stable, rigid casing, which helps with overall dry performance but is not so great for ride comfort or noise. 

Casing strength is vital for fast steering/vehicle response as well as cornering traction. We sometimes will use additional sidewall steel belts to further improve steering/vehicle response. This feature is rarer on a street tire. 

Other parts of the tire, such as bead and sidewall design, can also differ on an R-compound due to the anticipated race use, so we forgo ride comfort and rolling resistance in order to optimize heat dissipation, rim contact and increased response.

Compound design is more complex and is a highly guarded secret within most tire companies, so I can’t say too much. All I can say is that R-comps intended for dry use will be engineered to warm up quickly, resist high temps, and provide great traction at the expense of tread wear. 

The compound will be engineered to work within a specific temperature window, so performance drops off greatly when the temperatures get closer to freezing or get too hot. We have usage and storage guidelines for winter conditions because race compound tires will crack when the temperature drops too low. Another caveat is race compounds typically don’t work well on wet and slippery surfaces.

GRM: Why do R-comps run cooler than true street tires, and how does this translate into longer tire life and better track manners? 
Maxxis: Large tread blocks and a shallower tread depth generate less heat and also dissipate heat better.

Heat is usually the number-one enemy for tires. We haven’t done specific studies on tire life versus running temperature, but in general we know heat ages a tire faster and durability goes down as the tire is exposed to extended periods of heat. 

Regarding track manners, the mechanical properties of different tire components start to degrade with increasing heat, hence the performance drop-off you experience when the tires gets hotter and hotter. 

Due to the inherent design advantages–shallow tread depth, large blocks, construction materials–R-comps tend to run cooler than street tires on track, so even though they have shallower tread, they may actually last longer than street tires. The bigger/shorter tread blocks on R-comps also have higher rigidity, so they can withstand the abuse more and not chunk or wear rapidly.

Why? Because the 200-treadwear tires should run hotter on track, so the tire wears faster at these elevated temperatures. Although R-comps have slightly less tread depth, if you maintain a cooler running temperature, they should wear slower than the 200-treadwear tires.

We probably need to do a back-to-back study on this, but I’d say for cars that are heavier–3000 pounds or more–R-compounds should last a bit longer than the fastest 200-treadwear street tires.

GRM: Is there a line or a point where you as a tire engineer say that it’s time to move to an R-comp tire? 
Maxxis: It really depends on the individual, because some people want the fastest street tires available so they don’t have to swap tires for track days–that customer will most likely purchase the fastest 200-treadwear tires and doesn’t mind that the tires only last two track days.

GRM: What compromises are being made when running a 200-treadwear tire on track? 
Maxxis: We haven’t dissected them all, but the fastest 200-treadwear tires wear out pretty quickly. Some 200-treadwear tires may be heavier due to the deeper tread therefore you can sometimes improve your unsprung mass by switching to R compounds. Yes, tread wear seems to be an issue that tire companies haven’t been able to overcome.

GRM: Is there a downside to running R-comps?
Maxxis: Besides the obvious wet weather performance sacrifice, they don’t work very well when street driven: bad traction at low temps, bad traction on slippery surfaces, uncomfortable ride, significant pattern noise, poor rolling resistance. I can’t think of any downsides of running R-comps on track.

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Comments
View comments on the GRM forums
David S. Wallens
David S. Wallens Editorial Director
5/13/20 12:55 p.m.

I have a question to the question: What other tire questions does the group have? Experts are standing by.

Thanks. 

DirtyBird222
DirtyBird222 UberDork
5/13/20 2:43 p.m.

Very interesting and entertaining Q&A. We've been running Maxxis VR-1s on our 94 Accord Champcar for the last two years and the Q&A segment about heat got the gears moving in my noggin about issues we've run into with the VR-1 in a hot setting. Sebring in September for a 14 hour race, I can't think of a more brutal venue for a tire when you factor in all variables such as heat, track surfaces, speeds, and so on. Once the track got hot in mid-day we started losing corner exit grip on the VR-1s, they would bite in great on entry; but, as the car apexed it would start to plow. At night when things started to cool off they went back to the same driving characteristics we had in the early hours of the race and eventually to a class victory. As mentioned, the heat also caused much more wear on the tires than our previous race in a much cooler setting. 

David S. Wallens
David S. Wallens Editorial Director
5/13/20 3:36 p.m.

I wonder, would shaving the VR-1 tires help? 

Patientzero
Patientzero Reader
5/13/20 4:04 p.m.

How similar is the actual compound between the street and r-comp?   On a street tire is the better wet grip 100% due to the tread design or does differences in the compound help too?

KentF (Forum Supporter)
KentF (Forum Supporter) Reader
5/13/20 4:28 p.m.

What would be the coldest storage temperature you would want to allow for the 200 treadware and the R Comp tires?

David S. Wallens
David S. Wallens Editorial Director
5/13/20 6:35 p.m.

Good question and keep them coming. Spoiler alert: There's a part 2 in the works. 

Emilio700
Emilio700 New Reader
5/13/20 7:32 p.m.

In reply to David S. Wallens :

In our experience, yes. We were one of the race team asked to participate in early testing durin the development of the VR1 and RC1. Heat cycling is just heat x time. The longer the tread is exposed to heat, the harder it gets. The deeper the tread, the more it deforms, which generates more heat. The extra rubber mass also holds more heat. So a shorter tread has the double benefit of generating less heat and shedding whatever thermal load much faster than a full tread. Wehave shaved VR1's and RC1's for various events. Quicker than full tread and they actually last nearly as long. Proble is few shops still shave tires, fewer still know how to do it right and it ain't free. 

Emilio700
Emilio700 New Reader
5/13/20 7:37 p.m.

In reply to Patientzero :

Surprisingly, we have seen some of the latest 200tw EHP (extreme high performance) tires have lower durometer and faster wear rates than some older 100tw race tires. The softest wet specific race tires like a Hoosier H2O are actually designed to generate casing heat in the rain. They are fast in the rain even when cold but surreal once they heat up. Normal to come off track on full rainy day on H2O's and they're steaming, too hot to leave your hand on. The lack of sipe(tread grooves) and casing design are major factors in performance. EHP's ride like crap and are noisy. That's not tread design, that's casing design. The best current EHP's (A052, RE71R are far more sophisticated than the 100tw race tires of 15 years ago, like the NT01 for example.

adam525i (Forum Supporter)
adam525i (Forum Supporter) HalfDork
5/13/20 8:47 p.m.

I liked this line "Yes, tread wear seems to be an issue that tire companies haven’t been able to overcome."

Jeez, I wonder why that is? lol

Anyways, very interesting and I'm looking forward to part 2 (also looking forward to eventually upgrading from 200 TW to R).

Vigo (Forum Supporter)
Vigo (Forum Supporter) MegaDork
5/13/20 10:56 p.m.

Im curious about the distribution of how tires shed heat. As in, how much goes into the rim, how much goes across the contact patch, how much goes to outside air, etc. This is just pure curiosity. 

carpeforza
carpeforza
5/14/20 7:38 a.m.

Up here in the North, we have track days and races early in the season with track temps right around freezing. Even worse, we have sessions only 15 minutes long and sometimes raining / snow. What type of tire would give you the fastest lap times for cold, wet, short race sessions?

frenchyd
frenchyd PowerDork
5/14/20 7:53 a.m.
adam525i (Forum Supporter) said:

I liked this line "Yes, tread wear seems to be an issue that tire companies haven’t been able to overcome."

Jeez, I wonder why that is? lol

Anyways, very interesting and I'm looking forward to part 2 (also looking forward to eventually upgrading from 200 TW to R).

Think of it this way. Kleenex tissue companies haven't figured out a way to continually reuse Kleenex either. 
Actually there is a way to get long wearing tires.  Use harder treads. Race with TW600. 

David S. Wallens
David S. Wallens Editorial Director
5/14/20 8:16 a.m.

In reply to frenchyd :

Or go slower. 

David S. Wallens
David S. Wallens Editorial Director
5/14/20 8:25 a.m.

I have joked with friends in the tire biz: Why can't you make a tire that's really fast and also long-wearing? Oh, and I only want to pay $75 for it. 

aw614
aw614 Reader
5/14/20 8:27 a.m.
carpeforza said:

Up here in the North, we have track days and races early in the season with track temps right around freezing. Even worse, we have sessions only 15 minutes long and sometimes raining / snow. What type of tire would give you the fastest lap times for cold, wet, short race sessions?

I wonder how the continental extreme contact or michelin p4s would hold up for those cold sessions, and as the day goes on swap to the 200tw stuff later on?

David S. Wallens
David S. Wallens Editorial Director
5/14/20 8:29 a.m.

In reply to aw614 :

FWIW, you do often see those tires in One Lap. 

collinskl1
collinskl1 Reader
5/14/20 9:10 a.m.
Patientzero said:

How similar is the actual compound between the street and r-comp?   On a street tire is the better wet grip 100% due to the tread design or does differences in the compound help too?

Compound and tread pattern both have a role. A "slick" tire with a good wet compound would be fine in damp/wet conditions with no pooling or running water, as hydroplaning would not be a consideration. The rubber compounds trade off fillers between carbon black and silica to tune dry/wet performance. Of course, it's waaaaayyyyy more complicated than that, with all the other performance considerations.

DirtyBird222
DirtyBird222 UberDork
5/14/20 9:47 a.m.
Emilio700 said:

In reply to Patientzero :

Surprisingly, we have seen some of the latest 200tw EHP (extreme high performance) tires have lower durometer and faster wear rates than some older 100tw race tires. The softest wet specific race tires like a Hoosier H2O are actually designed to generate casing heat in the rain. They are fast in the rain even when cold but surreal once they heat up. Normal to come off track on full rainy day on H2O's and they're steaming, too hot to leave your hand on. The lack of sipe(tread grooves) and casing design are major factors in performance. EHP's ride like crap and are noisy. That's not tread design, that's casing design. The best current EHP's (A052, RE71R are far more sophisticated than the 100tw race tires of 15 years ago, like the NT01 for example.

You left out RS-3/4. At least for a FWD race car. We could get 40+ hours of racing out of a set and never felt performance peel back over the life. 

Coupefan
Coupefan Reader
5/14/20 10:47 a.m.

I won't  even bother looking at the list of available sizes, as I'm almost certain they're not catering to vehicles with smaller wheel diameters. 

L5wolvesf
L5wolvesf Reader
5/14/20 6:48 p.m.

How would these work on a dirt oval that is restricted to DOT tires?

GameboyRMH
GameboyRMH MegaDork
5/15/20 2:02 p.m.
Coupefan said:

I won't  even bother looking at the list of available sizes, as I'm almost certain they're not catering to vehicles with smaller wheel diameters. 

There are plenty of good tires still being made for 15" wheels.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
5/15/20 2:44 p.m.
David S. Wallens said:

I have a question to the question: What other tire questions does the group have? Experts are standing by.

Thanks. 

I would LOVE to get deep into tire tech.  I would love to know what goes INTO a tire and what those quantities produce in terms of qualities.... like higher plutonium content increases sticktion, increased dilithium crystals helps keep it more stable in wider temps, more dicktonium prevents UV damage, etc.

I know a little about tread patterns and how certain blocks do better in mud, snow, dry, quiet, rain, etc, but I've always had to trust the manufacturer that when they say 300TW and "all season high performance" that they will fall into a certain category... and I'm usually disappointed by at least one advertised parameter.

I want to know all there is to know.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
5/15/20 2:57 p.m.
David S. Wallens said:

I have joked with friends in the tire biz: Why can't you make a tire that's really fast and also long-wearing? Oh, and I only want to pay $75 for it. 

I totally understand that and this kinda points up my previous post.  Take for instance brake pads or clutch material.  The different materials that go into them all have pros and cons, but the mingling of possible combinations of those materials can make them more than the sum of their parts.

- brake fade/temp
- longevity
- noise
- dust
- brake torque

Of those qualities, manufacturers have been able to mix and match ingredients so that it isn't a direct trade-off.  You can have brake pads that excel at both dust and fade (ceramic), or pads that provide good brake torque and longevity (semi-metallic) etc. I'm wondering how those ingredient-mingling properties work for tires.... or if I'm just making assumptions that aren't really valid.  I don't expect to be able to formulate a magic tire for $75, but I feel like tires are advertised like a parts store advertises brake pads:  You get the value line, the silver line, or the gold line without really knowing what is in the box.  At least with brakes, you can open the box and see what you're getting.  I feel like tire manufacturers just write up marketing blurbs about how "this tire has exceptional performance for your family sedan in most categories, and is also good at everything else, and they have a 360 TW.  Good luck guessing how they'll actually suit your driving style."

z31maniac
z31maniac MegaDork
5/15/20 3:45 p.m.
David S. Wallens said:

I have joked with friends in the tire biz: Why can't you make a tire that's really fast and also long-wearing? Oh, and I only want to pay $75 for it. 

Quintessential GRM. :)

"Yes, why isn't Ford building a track-ready, four-door wagon, with 500hp, manual gearbox, and RWD for $18,990?"

dps214
dps214 Reader
5/15/20 4:07 p.m.
Curtis73 (Forum Supporter) said:

Good luck guessing how they'll actually suit your driving style."

For one thing, "driving style" doesn't really become a factor until you're talking about competition tires. Beyond that, a big part of the problem is it varies depending on what vehicle the tires are going on, what kind of driving you're doing with them, etc.

Olemiss540
Olemiss540 Reader
5/15/20 5:15 p.m.

Follow-up question. 

At what point will we see the 200tw super tires out today be able to hold up to 4 or 5 track weekends a year? Give me RC1 or NT01 grip levels that can handle 32 sessions while driving to/from the track please (potentially driiving to events in the rain). 

Also, was NT01 the target for your RC1 offering? Where do you see success in dethroning the ultimate HPDE tire and where do you see room left to improve? What causes a tire to better handle braking zones and why does one tire prefer to have higher angles of slip versus another in the same treadwear segment?

THANKS SO MUCH for building a tire in the 275/35/17 profile, it is awesome having an HPDE tire in this shape!

LanEvo
LanEvo Dork
5/15/20 7:15 p.m.

In reply to David S. Wallens :

I'm interested in the differences between high end R-comps (like Hoosier R7s) compared to true slicks (like Hoosier C3000s). Also, R-comps vs. asphalt circle-track slicks. 

Sonic
Sonic UltraDork
5/15/20 9:09 p.m.

In reply to Olemiss540 :

Hankook RS4 does this now.  We get 3 whole lemons weekends out of a set, that's 50 hours of track time.  

MrFancypants
MrFancypants New Reader
5/16/20 2:25 p.m.
Sonic said:

In reply to Olemiss540 :

Hankook RS4 does this now.  We get 3 whole lemons weekends out of a set, that's 50 hours of track time.  

I have about four track hours on my current set of RS4s and a few thousand street miles and they look like they're barely scuffed in.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
5/16/20 4:10 p.m.
dps214 said:
Curtis73 (Forum Supporter) said:

Good luck guessing how they'll actually suit your driving style."

For one thing, "driving style" doesn't really become a factor until you're talking about competition tires. Beyond that, a big part of the problem is it varies depending on what vehicle the tires are going on, what kind of driving you're doing with them, etc.

If that were true, there would be no test-and-review articles about tires.  companies like Tire Rack will pick a category and buy a set in every category, put them on the same vehicle with the same drivers and get vastly different results.  I have a 4x4 compact pickup.  The tires I chose for mine will satisfy me in PA, but not do so well for someone in Nebraska on the farm.  So yes, driving style has everything to do with it.

This is my whole point.  We either trust what manufacturers claim, or try to read between the lines of a review that may or may not exist.

wspohn
wspohn Dork
5/17/20 11:19 a.m.

Anyone remember the original BFG Comp TA R1 tires?  Not sure what the wear index on them was but those of us who ran them on the track sure did shave them first as they lasted far better and didn't build up enough heat to chunk.

David S. Wallens
David S. Wallens Editorial Director
5/21/20 10:06 a.m.

The follow-up piece is coming together.

Thanks again for all of the interst in the topic. We could talk about tires all day. 

GCrites80s
GCrites80s HalfDork
5/21/20 10:58 a.m.
dps214 said:
Curtis73 (Forum Supporter) said:

Good luck guessing how they'll actually suit your driving style."

For one thing, "driving style" doesn't really become a factor until you're talking about competition tires. Beyond that, a big part of the problem is it varies depending on what vehicle the tires are going on, what kind of driving you're doing with them, etc.

Also the average non-competition driver has almost no self-awareness regarding their driving style and even plenty of competition drivers. Makes it tough to write ad copy.

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