Questions for a Tire Engineer: Why Can’t We Have It All?

Sponsored article presented by Maxxis Tires.


When it comes to tires, sometimes we just want it all.

Then a little thing called reality gets in the way. 

But why?” we all cry. “Why can’t we have it all?”

So we asked someone who can tell us why: John Wu, an engineer by training and now director of product strategy for Maxxis USA. John’s tenure in the tire industry goes back to 2005, but he’s been running track events for 20 years. 

Maxxis currently offers two tires aimed at the hardcore market. The Victra VR-1 is a 200-treadwear model that has found a home in today’s endurance racing scene. 

For those who want to go faster—and aren’t saddled with the 200-treadwear requirement—Maxxis also offers the Victra RC-1, an R-compound track tire carrying just a 100-treadwear rating. 

John answered some of those “But why?” questions that often come up when discussing high-performance tires. 

GRM: Why can’t you just use a softer compound to make the tire faster?
Maxxis: We must first clarify that a softer compound doesn’t automatically mean that a tire has great dry traction. For example, winter tires usually use a relatively soft compound, but its dry traction properties aren’t stellar at all. 

To answer the original question, compound engineers can always come up with a super-soft tread compound with great dry traction properties, but the challenge of bonding this compound with other parts of the tire, mixing this compound in large volumes, and making sure this compound can be processed easily can be hard to overcome. 

GRM: Why can’t you stick your race compound rubber onto a street tire to make a really fast street tire? 
Maxxis: The issue isn’t that the tire companies can’t do it. The issue is doing it efficiently and with some profitability. 

The challenge is that race compounds are designed to work under specific conditions. From a production perspective, extruding this compound into a different shape—street tires have a different profile and deeper tread—and mixing this compound in great volume can be a challenge. 

From a usage perspective, the compound and construction may not be optimized for each other, so the footprint at the limit may not be ideal to generate the best dry lap times. 

A street tire also has deeper tread, so the tire can overheat and suffer from heat-soak and/or wear problems. On top of that, tread life and the long-term durability of the tire have to be considered as well. 

GRM: Why is it so difficult to engineer a fast tire? Why not simply copy the fastest tire out there and turn it up a notch? 
Maxxis: We wish it was that easy! We can always analyze our competitors and understand the mechanical properties and chemical makeup of the end product, but how did our competitor get there? The issue is similar to cooking: A chef can share a recipe, but it still takes the right equipment, the right process, and various chef skills to deliver at the same level. 

GRM: Why can’t you offer a tire that’s really fast, lasts for many laps, and only costs $75?
Maxxis: The trade-off between price–premium materials and manufacturing cost. Speed and wear continue to be an engineering/physical reality for the tire industry, but we are all working on shrinking the amount of trade-off. 

GRM: Why can’t you offer even more sizes?
Maxxis: Usually this is just a simple business decision when the extra mold won’t be paid off fast enough to turn some profit. Sometimes this has to do with production as well, when certain factories may have size limitations due to equipment. 

GRM: Why does tread design matter? 
Maxxis: For the GRM crowd that wants the fastest tire, a race slick is the ultimate solution if the vehicle is only used on dry surfaces. 

Unfortunately, once you need wet performance, engineers have to put in grooves to help expel water from the contact patch. The challenge is that most consumers don’t want their tires to sound like mud tires either, so designing and placing the grooves is a technology that continues to evolve.  

GRM: Why doesn’t a worn tire equal a race slick?
Maxxis: A worn street tire probably has thousands of heat cycles by the time it is worn down to a slick. Therefore, the compound probably doesn’t have much dry traction performance left due to thermal and oxidation aging. 

Also, some street tires feature something called tread base rubber. This is the layer of the tire that binds the actual tread to the cords and other inner components. So, when the tires are worn down to a slick, you may be driving on this tread base rubber, which has almost no dry traction properties. 

GRM: Why can’t I keep using my street tires even though they’re at the wear bars?
Maxxis: Once the tread is worn down to the wear bars, there is just not enough void in the tire to evacuate standing water to prevent potential hydroplaning. The pattern is also usually worn out so much that they’ve lost significant wet traction properties as well, so we recommend that our customers replace tires at the wear bars. 

GRM: Why can’t I drive my R-compound tires in the winter? 
Maxxis: Driving a summer-oriented tire—not just an R-compound—in the winter may lead to cracking issues. Rubber compounds have a temperature at which they become brittle like glass, aka the glass transition temperature; therefore, engineers develop compounds with various glass transition temperatures and then select the appropriate compound for the intended purpose. Since most racing doesn’t take place during winter, we don’t design R-compounds for winter temperatures.  

GRM: Why does tire performance fall off when driving many laps in a heavy car on a hot summer day?
Maxxis: Most tires will experience fatigue because the tire’s mechanical properties change when conditions get hot, and the compound traction properties can change as well. Of course, we can engineer or find new materials that handle heat better, but incorporating it into a complex production process at a reasonable cost is a big challenge.

GRM: Why doesn’t my W speed rating mean that I can drive at 168 mph all day? 
Maxxis: The way the industry certifies speed ratings is based on laboratory testing only for assuring the durability at maximum speed. Tire companies need to test at a specific load and inflation pressure and not have any issues running at 168 mph for a set amount of time. 

Since tire companies can’t anticipate all the different outside variables (weather, vehicle condition, tire condition), we recommend that customers see the speed rating as a reference and not a ticket to drive at the tire’s maximum rated speed for an extended period of time.

To read more questions and answers like these, head over to our previous tire discussion with Maxxis.

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Comments
View comments on the GRM forums
David S. Wallens
David S. Wallens Editorial Director
5/29/20 10:50 a.m.

And I know that everyone's still after the elusive tire that does it all: fast, long-wearing, easy to drive, huge size range and only costs $75. Hopefully some of these answers show why that's such a tall order. 

P3PPY
P3PPY HalfDork
5/29/20 1:31 p.m.

Very cool - the one about slicks vs. bald has been on the top of my tire question list for some time now

dps214
dps214 Reader
5/29/20 1:42 p.m.

The article touches on it a little bit but I've been curious for a while about what exactly the requirements for speed rating are, especially when most of the ratings are only separated by a few mph each. I've had some snow tires with super low ratings that I've either come close to or have exceeded the rating on for brief periods of time. At one point I asked a tire engineer friend and it seemed like either they didn't know or they weren't very firm guidelines.

David S. Wallens
David S. Wallens Editorial Director
5/29/20 2:48 p.m.
P3PPY said:

Very cool - the one about slicks vs. bald has been on the top of my tire question list for some time now

And I guess I forgot that snow tires also feature soft compounds. (Once John mentioned that, pretty sure I learned that at a winter driving program.) So, yay, we're learning stuff. 

Vigo (Forum Supporter)
Vigo (Forum Supporter) MegaDork
5/29/20 11:15 p.m.

Another good one! Appreciated!

cbaclawski
cbaclawski New Reader
5/30/20 8:46 a.m.

Compared to years past, we DO have it all!  It's just that as technology advances, and the baseline moves, so do our expectations.  A modern all season is likely both faster, longer lasting, and cheaper(inflation adjusted) than anything from the 70's.  The competition will always be to have the fastest, longest lasting, quietest, etc. of what is CURRENTLY on the market.  As performance increases, We'll always want more!  (and thus never reach nirvana)

BimmerMaven
BimmerMaven New Reader
5/30/20 6:55 p.m.

In reply to cbaclawski :

right-on!

if memory serves, we've gone from 0.5g street, 0.7g sport, and 1.5g race tires in the 60s progressively to 0.7, 1.2, and 3.0g now

and they cost less

and they are better in the wet

and they last longer.

I think R&T declared that tire tech is the single largest factor for better handling cars "now".  SUVs out-hande many sports cars from 60-70s 

tire engineers are yet another "un-sung hero"!

Olemiss540
Olemiss540 Reader
5/31/20 7:56 p.m.

It still amazes me that the NT01 has yet to be dethroned after quite a few years of being on top of the dry weather HPDE performance category. Grip, treadware, cost, heat resistance, etc, etc.

collinskl1
collinskl1 Reader
6/1/20 8:29 a.m.
Olemiss540 said:

It still amazes me that the NT01 has yet to be dethroned after quite a few years of being on top of the dry weather HPDE performance category. Grip, treadware, cost, heat resistance, etc, etc.

It has been eclipsed by several tires at this point... The 200 Treadwear category is almost all better than the NT01.

Olemiss540
Olemiss540 Reader
6/1/20 11:12 a.m.
collinskl1 said:
Olemiss540 said:

It still amazes me that the NT01 has yet to be dethroned after quite a few years of being on top of the dry weather HPDE performance category. Grip, treadware, cost, heat resistance, etc, etc.

It has been eclipsed by several tires at this point... The 200 Treadwear category is almost all better than the NT01.

Not in any testing I have seen or real world experience from those running them. The RE71R might be able to run head to head (or even be a touch quicker) but it has a narrow window before its overheated or heat cycled and is quicker wearing. The a052 is an autocross tire that cant handle the heat of DE sessions and wears amazingly fast, the rs4 is not up to pace but has the longevity. What am I missing?

The NT01 wears slow, is extremely heat resistant, and most wear them to the chords as they get quicker and quicker. I have gotten 35-40 HPDE DAYS out of a set on NT01s.

jharry3
jharry3 HalfDork
6/1/20 11:25 a.m.
David S. Wallens said:
P3PPY said:

Very cool - the one about slicks vs. bald has been on the top of my tire question list for some time now

And I guess I forgot that snow tires also feature soft compounds. (Once John mentioned that, pretty sure I learned that at a winter driving program.) So, yay, we're learning stuff. 

Old drag racers trick from way back. Use snow tires in street tire classes.  More grip off the line because of the softer compound.   Probably no longer relevant because of the better tire compounds of today.   

David S. Wallens
David S. Wallens Editorial Director
6/1/20 7:44 p.m.

In reply to jharry3 :

Sort of related to the snow tire idea, check out this piece about Old Yeller II on the Classic Motorsports site. Max Balchowsky ran white walls because they were softer. 

cbaclawski
cbaclawski New Reader
6/1/20 9:41 p.m.
Olemiss540 said:
collinskl1 said:
Olemiss540 said:

It still amazes me that the NT01 has yet to be dethroned after quite a few years of being on top of the dry weather HPDE performance category. Grip, treadware, cost, heat resistance, etc, etc.

It has been eclipsed by several tires at this point... The 200 Treadwear category is almost all better than the NT01.

Not in any testing I have seen or real world experience from those running them. The RE71R might be able to run head to head (or even be a touch quicker) but it has a narrow window before its overheated or heat cycled and is quicker wearing. The a052 is an autocross tire that cant handle the heat of DE sessions and wears amazingly fast, the rs4 is not up to pace but has the longevity. What am I missing?

The NT01 wears slow, is extremely heat resistant, and most wear them to the chords as they get quicker and quicker. I have gotten 35-40 HPDE DAYS out of a set on NT01s.

35-40 days?!?  What car?  I feel lucky if I get 3 days!  (not NT01's, never really tried those, but maybe I should...)

David S. Wallens
David S. Wallens Editorial Director
6/1/20 9:55 p.m.

A fellow tire engineer once posed a scene: Picture all of the forces that a tire endures in one revolution. You have the g-forces trying to pull it apart, then you slam the tread into the ground before you drag it across the pavement. And that's before even bringing up turning, braking or acceleration. Or rain, snow, ice or a 75,000-mile warranty. There's a lot going on. 

Olemiss540
Olemiss540 Reader
6/3/20 8:46 a.m.

If the A052 could handle 4 or 5 weekends (HPDE), it would be pretty perfect. Sadly many of the reviews talk 3 or 4 DAYS!

David S. Wallens
David S. Wallens Editorial Director
6/5/20 1:00 p.m.
P3PPY said:

Very cool - the one about slicks vs. bald has been on the top of my tire question list for some time now

I remember back in the day you'd see dudes with totally worn-out tires claiming that they were now faster. Um, likely no. 

noddaz
noddaz UltraDork
6/5/20 4:28 p.m.
David S. Wallens said:

I remember back in the day you'd see dudes with totally worn-out tires claiming that they were now faster. Um, likely no. 

Well, maybe.  A worn tire that is not totally gone would have a smaller diameter and weigh less.  Until you hit the last layer and the tire is gone.  Of course it could just be "now I know the track better" also.

Just guessing.

dinesh
dinesh New Reader
7/4/20 7:33 p.m.

Thats an insightful discussion! Great

Toebra
Toebra Dork
7/5/20 3:45 p.m.

Tires, like life, always involve compromise.  That is why you want a second set of wheels

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