Tire opinions

[Tom Berry]

Another "Lemons" race coming up!!
We are concidering 3 tires for the race.
- Dunlop Star spec
- Azenis RT615
- Azenis RT615k
Tire size 205/50/15 on a E30 BMW Oh yea... 190 tread wear or higher.
Anybody have Data? Suggestions? Opinions? Etc...

[Steve Ekstrand]

I don't like any of the three for long lapping on a relatively heavy car for that size.

I'd be thinking Kumho XS, Bridgestone RE-11 or why not the 225-45-15 Hankook's. The kook's like the heat, are a little larger, cheap, and LAST.

If you're tied to the original three, the 615 doesn't like heat. And its quite a ways down on grip compared to the current crop of top tires. I haven't tried the K. I love the star spec's on my bimmer, but they are 265-40-18's.... Little different animal.

[Jeff Wong]

190 treadwear or higher.

[Arthur Grant]

Tom, I don't have any personal experience but there is an article (well written I might add) on motor IQ by a guy who has won several of these events. Might be worth your time to review, he includes photo's and video. He recommends and uses asenis rt-615K. I have included the text of the article.

http://www.motoiq.com/magazine_articles ... 615-k.aspx" onclick="window.open(this.href);return false;

The typical new tire introduction goes like this: The new Pazoosy Jaberwoky XR 745 Ultra R Super Star uses triple-inverted diagonal ply Inconel belts and a directional, asymmetrical tread pattern to optimize wet and dry grip, minimize road noise, increase your fuel economy and magnify your sex appeal. The sad truth is that neither the author, nor the PR team that fed him that line of technospew has any idea what triple-inverted diagonal ply Inconel belts are or what they do.

That's what makes this tire review great. I have no idea what Falken did to change this tire. The new Azenis RT615-K is just as round and black as the Azenis RT615 it replaces. In fact, the tread pattern is the same, most of the sizes are the same, and really the only visual distinction is the little "K" on the sidewall.

I do know that I'm a fan of the old Falken Azenis RT615. It wasn't the grippiest tire on the market, and it wasn't the cheapest, but it seemed to occupy a happy balance of cheap enough and sticky enough to be on your daily driver, your track car, or your car that happens to be both. I've pulled 1.0g with Project Silvia on these tires, I've done 1500 mile road trips on these tires, and I've endurance raced on them.

We've been running the 615s on our LeMon for 11 very successful races, capturing 4 outright victories and more top 5 finishes than we can be bothered to keep track of. Even at that pace, our tiny 195/60-14s easily last through the 14 or so hours that make up almost every 24 Hours of LeMons and still have enough life left that the ones that aren't hopelessly flat spotted still have at least a track day's worth of hoonassery left in them.

At this year's Going For Broken race at Thunderhill we stumbled into a unique tire testing opportunity. We had 6 used, but still very serivceable RT615s in remarkably good shape after running a full 14 hours at Infenion Raceway and winning the Sears Pointless race. We also had 4 new RT615-Ks. Same car, same track, and over 2 hours of racing on each to sort out the differences.


The scientists among you have already spotted the one massive variable in this test of opportunity. The old tires were, indeed, quite old, with a full race under their belts already. Sears point had been remarkably easy on the tires, though, and remember those 11 previous races we've done on the same kind of tire. We know exactly what the RT-615 feels like on our car, and these, though a little square, were still in good shape. At most, fresh RT-615s might have been one second faster.
So, finally, what's the difference? About 3 seconds (or 2, if you want to assume our old tires were 1 second off their peak), knocking our fastest lap of Thunderhill (counterclockwise, full track, without the turn-5 bypass) from a 2:16:somethingorother to a 2:13:andalittlebit.

The RT-615-K has more raw grip than the old RT-615, but more importantly, its much easier to drive. The limit behavior is more forgiving, with smoother breakaway and more grip at high slip angles that makes them easier to control at the limit and beyond. This breakaway character manifestes itself in some unexpected ways.

The damping from our tired old stock Miata shocks actually felt better with the new tires. Softer sidewalls? I don't think so. The sudden breakaway of the old tires, coupled with the extra weight of an 80-lb starship on the roof of our car, caused some sudden roll inputs into the chassis on turns 14 and 15 (a tight, 180-degree combination with several curbs and rumble strips) that would send the car into the bump stops and set up a very unprofessional bouncing, porpoising corner exit. With the 615-K, the smoother limit behavior meant breakaway and recovery weren't violent enough to over-work the suspension. The result was smoother car that suddenly felt like the shocks weren't 17 year old.


Braking performance was also much better. Since we started running our Frankenmiata, we've complained that the brakes are too front-biased and lock easily. We almost never manage to wear one of the 615s all the way down before an accidental lockup makes the tire too square to keep using. During the 8 hours we've run the 615-K, we haven't made a single flat spot. Not only does the increased grip help braking distances, but that smooth limit behavior makes the brakes easier to modulate at the limit, so its easier to unlock a locked wheel before things go all square.

Finally, the new compound seems more heat resistant. During our "test" I got into a 90-minute battle with Spec Miata driver Dean Thomas in the Death Cab Ford-302-powered Volvo 240. I pushed the car hard for much longer than I normally would in a LeMons race, trying desperately to put some distance between myself and that giant Volvo bumper. Past experience suggests the same level of aggression would have overheated the old tires, causing them to go a little greasy. The 615-Ks held up to the flogging with no appreciable change in performance.
In short, the new Azenis RT-615-K costs a few bucks more than the old RT-615. Its worth it.

Want to see the "test" in progress? Check out these videos: (visit the link above)

[John Coffey]

IMHO, I would buy the cheapest tires I could find, shave them, and have multiple sets. The Kumho Ecsta AST is $58 each in the size you list. Use the extra money for spare parts.

[Eric Clements]

If you want spare/backup tires I have some Hankook RS-2's and some really old Falken 215's. Price is right, free, but you have to take both sets

[Doug Kott]

Hi Tom,

To be competitive, you'll need something with decent grip. Hard to beat the Direzza Star Specs for your application, and they're priced right too. They're selling at a bit of a discount now at Tire Rack, IIRC.

--Doug

[Jayson Woodruff]

Aren't the tires excluded from the vehicle cost limit?

Jay W

IMHO, I would buy the cheapest tires I could find, shave them, and have multiple sets. The Kumho Ecsta AST is $58 each in the size you list. Use the extra money for spare parts.

[Tom Berry]

Aren't the tires excluded from the vehicle cost limit?

Jay W

IMHO, I would buy the cheapest tires I could find, shave them, and have multiple sets. The Kumho Ecsta AST is $58 each in the size you list. Use the extra money for spare parts.

.... yes.. tires are excluded from the $500

[Tin Bui]

Tom,

Are you racing the December Buttonwillow event? I'll be racing the event in an MR2, Spirit of Toyota F1 v13.b6.

We're in a dilemma of tires too. Grip vs Endurance vs Cost. Will one set last the event?

[Tom Berry]

Tom,

Are you racing the December Buttonwillow event? I'll be racing the event in an MR2, Spirit of Toyota F1 v13.b6.

We're in a dilemma of tires too. Grip vs Endurance vs Cost. Will one set last the event?

Yup... Wienershmocker III will be back at it. Assuming no alignment issues.... one set should last the event. Now brake pads might be a different story.
Your car?

[Tin Bui]

We picked up a non running MR2 from a kid trying to make it to a junk drifter. Let's say he has no mechanical ability, the entire head has either loose or stripped hardware.

We currently have 14" wheels that came with the car and 16" wheels off another car. Both are horrible wheel choices for the MR2 because there are not that many tires choices that have the good price and a good diameter (most are too tall). We're too cheap to get a set of 15".

For the 16" wheels we want to run a 205/40R16, maybe even try a 215/40R16. Stagger or no stagger.

That leaves the Falken 615K, BFG g-Force Sport, Falken ZE912, and the Toyo T1R (however too tall). The BFG and the ZE912 are good because of price.

ZE912 I hear are good tires, we use them on our entry level training cars at the proving grounds in Arizona.

[Max Likhterman]

I've had Azenis,Z star Specs and RE-11's on stock ( or near stock ) E21/E30. Azenis are not good unless you have enough camber to keep them flat during cornering( shoulders will be gone before you know it) and they don't like heat. Azenis is going to overheat in one lap just because it's warmer that 60F. Z star specs are much tougher, grip is better and they last longer. They have stiffer sidewalls so shoulders won't wear out as fast. Heat is OK too, never had the problem with them getting greasy. Now , RE-11's feel different, but they do not seem to last as long. They may be faster or the same, I did not notice the difference in times, but I'm not fast

Just my .02

Max

[Giovanni Jaramillo]

When purchasing from Tire Rack do most of you purchase TIRE RACK TIRE ROAD HAZARD SERVICE PROGRAM? Or it that a complete waste of money? ($102 for a set I'm about to purchase)

[John Coffey]

I use the free John Coffey Road Hazard Insurance: "Don't run over crap."

[Rick Brown]

I use the free John Coffey Road Hazard Insurance: "Don't run over crap."

Yeah, but isn't every vehicle on the track with you just a pile of crap waiting to come apart all over the place? Seems like the only way to use your insurance is to DNS.