How to pick the right tires for endurance racing | Project Endurance Race Miata

Tom
Update by Tom Suddard to the Mazda Miata project car
Dec 6, 2021

As our LFX-swapped Miata inches closer to completion, it’s time for an easy task: Ordering wheels and tires.

Except, well, that’s not so easy anymore. Because our Miata is destined for amateur endurance racing, we’ll need to shoe it with 200-treadwear tires. And, thanks to the 200-treadwear tire wars, there’s no longer a single best answer.

Choosing the best 200-treadwear tire for your application is a question of driver style, vehicle weight and power, desired lifespan, driving characteristics and sizing. Let’s solve the puzzle.

[Ultimate track tire guide | 200tw, 100tw, street-legal track and R-comps]

High-Horsepower Miata Endurance Racing Tire Sizing:

No, a 205/50R15 isn’t the answer here.

Sure, it’s the default for Miatas, but our goal is to complete an entire race day without changing tires, saving valuable time in the pits. Running with series like the World Racing League and American Endurance Racing means these days are often nine hours long.

How do you make a tire last longer on track? One answer is to bring more rubber with you. By choosing the widest size we could reasonably fit on our Miata, we’d get more life out of each tire.

So we went on the hunt for wider wheels, setting aside our trusty 15x7-in. Konigs for a future project. And our hunt lead us to the doorstep of Good-Win Racing.

Good-Win Racing sells a wheel designed for applications exactly like ours: the 15x10-inch Konig Dekagram. This flow-formed wheel weighs about 14.5 pounds–remember the 10-inch width when looking at that weight–while costing $239 each.

These wheels will even nearly fit under the fenders of an early Miata like ours. (We’ll still need flares or serious fender rolling.) Plus the kit will also clear our Wilwood big-brake kit.

We ordered two sets of these Konig wheels from Good-Win, so that should be enough to get our Miata through a weekend of endurance racing.

A 15x10-inch wheel calls for a wide tire, and Good-Win recommended we run a 245/40R15. Time for the next phase of the hunt: tire selection.

High-Horsepower Miata Endurance Racing Tire Selection:

Choosing an endurance racing tire isn’t rocket science, but it takes a spreadsheet and some careful thought. Here’s how we did it.

First, sizing: 245/40R15 is far from a dead size, but it’s also not the most common choice. In fact, Tire Rack only shows three 200tw options in this size: BFG’s G-Force Rival S 1.5 ($209/tire), Hankook’s Ventus R-S4 ($148/tire), and Falken’s Azenis RT660 ($160/tire).

There are some other options available outside Tire Rack, too: The Maxxis Victra VR-1 ($166/tire), as well as the Valino Pergea 08R (out of stock) and of course Nankang’s CR-1, which will be renamed the CR-S shortly ($189/tire).

[200tw Tire Test | Valino and Yokohama take on favorites from Hankook, Maxxis, Bridgestone and BFGoodrich]

We have our field, time to start eliminating competitors based on our previous tire tests and advice from Andy Hollis, our resident tire expert.

The first elimination: durability. We knocked out the tire we didn’t think would have a reasonable chance of withstanding nine hours under our 300-horsepower Miata, which meant the RT660 had to go.

Next up: speed. We’ve tested every tire on the list, which is how we knew which tires wouldn’t keep up with the top contenders. We waved good-bye to the R-S4, Victra VR-1, and Pergea 08R.

It was time for the final elimination: With two tires left, the BFG Rival S 1.5 and Nankang’s CR-1, we faced a tough decision.

The Nankangs cost a little less, but would they last the full nine hours on track? Would choosing the BFGs meant spending more time in the pits while facing a higher tire budget? 

After careful deliberation, we ordered two sets of Nankang’s CR-1. After all, it’s our job to try new things, and we’re excited to see how these hold up under our Miata.

We mounted our new Nankangs on our new Konig wheels, and went back to work on the rest of the car: We’re nearly ready to get on track.

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Comments
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Captdownshift (Forum Supporter)
Captdownshift (Forum Supporter) MegaDork
12/3/21 3:32 p.m.

It smells like a new tire test may be needed as well, a 12-15 flying lap test to see which ones keep their speed beyond 20 minutes without becoming greasy and falling off. Knowing how well the nankangs perform under braking, on a platform such as the Miata that doesn't suffer from brake fade issues when properly setup, I feel that you made the correct decision. For a heavier platform with brake cooling concerns, the Rivals or RS-4s may have been the answer. 

Ed Higginbotham
Ed Higginbotham UberDork
12/6/21 11:52 a.m.

Curious about the reasoning behind eliminating the Falken RT660 right out of the gate. We're planning on doing an AER event or two in my E36 this year and I was targeting the Rt660s since they seemed like a decent across-the-board option from the Ultimate Track Tire Guide and are very reasonably priced. (Awesome tool by the way!) What made it seem less durable? Obviously durability is a major factor for AER.

fatallightning
fatallightning Reader
12/6/21 1:42 p.m.
Ed Higginbotham said:

Curious about the reasoning behind eliminating the Falken RT660 right out of the gate. We're planning on doing an AER event or two in my E36 this year and I was targeting the Rt660s since they seemed like a decent across-the-board option from the Ultimate Track Tire Guide and are very reasonably priced. (Awesome tool by the way!) What made it seem less durable? Obviously durability is a major factor for AER.

I believe testing has shown them to be very RE71 like in terms of speed and durability. So a true ripper, but not long for this world.

Ed Higginbotham
Ed Higginbotham UberDork
12/6/21 1:49 p.m.

So what I'm hearing is paying a couple extra doll hairs for the Rival S is probably a good call for AER, yes? It's not a high-horsepower car. It's a NASA Spec3 car. So max power is 189 hp. Weight around 2800.

APEowner
APEowner GRM+ Memberand SuperDork
12/6/21 4:32 p.m.
Ed Higginbotham said:

Curious about the reasoning behind eliminating the Falken RT660 right out of the gate. We're planning on doing an AER event or two in my E36 this year and I was targeting the Rt660s since they seemed like a decent across-the-board option from the Ultimate Track Tire Guide and are very reasonably priced. (Awesome tool by the way!) What made it seem less durable? Obviously durability is a major factor for AER.

Of the tires on that lis the only ones I have experience with are the RT660s.  They're our spec. tire for the Spec. Miatas at Sandia speedway.  At the pointy end of the field we get about 3 hours from a set before the cords are showing.  That's in 20 minute sessions with tire rotations.   Sandia does have a notoriously abrasive surface but even double that life won't get you nine hours.

 

Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
12/6/21 4:49 p.m.

Disclaimer: I haven't personally driven on RT660s. 

But Andy made it clear that we wouldn't get 9 hours out of them in our Miata. Your BMW might be better thanks to less power and aero, but it's also heavier. The Rival S is a fantastic choice. 

 

Ed Higginbotham
Ed Higginbotham UberDork
12/6/21 5:28 p.m.

Rivals it is. Thank you everyone for the excellent feedback. I very nearly made a pretty terrible tire choice for our application. 

Tom, are you guys running the AER race at VIR??

kevinatfms
kevinatfms GRM+ Memberand HalfDork
12/7/21 9:38 a.m.

We just destroyed RT615k's at the VIR North race in Champ Car with a whacked out alignment after some agricultural excursions. I cannot thank Falken enough for making the tire that resilient to damage as we cooked the E36 M3 out of them lap after lap.

Ill post up pictures of the tires and our alignment settings after i went off and flat out ruined the alignment in hour 4 of the first day.

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
12/7/21 9:45 a.m.

I'm sort of surprised the rs4 and maxis vr1 (v2) wasn't considered to be on the pace.

 

Also, do they not yet make the continental (hoosier) in that size yet?

 

Also, what about the rs3r?  They make it in that size (not sure if available yet).

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