O.P.T.: a tracktard tip

After two days at Summit Point my brand new Kumho v710 looked like what you see at the bottom of the above picture. A heat gun, a good quality spatula and about a half hour later, I removed 2.5lbs (1.4kg) of Other People's Tires from mine. I think this will become part of my track routine.

And here is the rest of it.

Wear and Tear

Shop for KUMHO tires at Tire Rack.

Collectively we do a fair amount of track days during the season and readers might get the impression that everything is all just fun and smoking brake pads but the truth is that inevitably our cars suffer from the wear and tear inherent in...well, let's just say we are not especially kind to the poor things.

Sure, CG took a crow bar to his 997's fenders when he realized his new tires would not fit the day before a track day, but file that under self inflicted hardcore insanity. Parts do break on their own when street cars are run hard, so we will examine some of the issues we had and some that we'll address in the off season.

In the pictures below you can see the little surprise I got at the end of my last session of the day at Watkins Glen earlier in the year .
This SSR Comp had one spoke cracked clean through. The scariest part was that I only noticed as I was packing up the wheels at the end of the day. I have no actual clue as to when during the day this happened and I do not remember noticing anything especially wrong on track.

What had drawn my attention to this wheel was the unusual wear pattern on the tire. While my car usually wears the tires very evenly, this Kumho V710 was cupped (orange line) and especially it had an odd regular pattern of flat spots (green arrows) which I found extremely odd. I wonder if the cracked spoke caused some sort of odd vibration to occur.

In any case, the thought of what might have happened was enough to have me checking all wheels after every session since, I recommend all you fellow track rats consider doing the same at least occasionally.

Go black and you won't go back.

If you do your share of driving at the track chances are your wheels look like crap. Race pads and heat and rubber will turn your nice lightweight rims into rusty crusty nasty alloy donuts. This is especially painful if you happen to like a particular breed of pads, Performance Friction PF 97 being a prime example, which produce a dust with the charming habit of turning into a rust crust so hard it can only be taken off with oven cleaner. This will happen if the dust gets wet and dries.
I got sick of getting mad about wheels looking crappy so I decided to paint my SSR track wheels black. This is key to happiness: no more obsessive cleanings, no more crappy looking wheels.

It's very easy to do for yourself, and don't stress too much over it remember that your wheels already look like crap!.

Start with as good a cleaning, use a de-greasing agent. Give it a good once over with a scotch-brite pad. Put masking tape on the valve stem.

Get a can of Dupli Color High Performance Wheel Coating at your local auto parts store. I like matte black (which ironically is not matte at all). Shake well.

No need to take the tire off, nobody sees the inside of your wheel under the tire, only your tire mounter will know for sure.

Use cardboard as a quick mask. If you get a tiny amount on your race tire and get all upset about it just remember this: if you are driving properly that tire will be gone VERY soon....oh, and it's black anyway.

Go at it in multiple light coats, it will need to dry about 10-15 minutes between coats. The stuff is great and as long as you don't put it on too heavy will sort of self level and make a very even coat. Let dry overnight.

Now the best part is that after you have done your initial painting and you come back from the track with nasty wheels like the ones above, a quick wipe and degrease and a quick spray and you are back in top form. Scratches? no problem, spray and go.

It's fucking greatness as Jebbe would say.

Ever wonder how your tire feels?

I was curious so when we were at the last Pocono East track day with PDA, I attached a camera to the bottom of the MCoupe. The camera is pretty cheap but you do get an idea of what your tire goes through on a typical day out.

In this case you can see my Kumho V710's contact patch change as the tire loads and unloads. When it's unloaded only a quarter or less of the tire touches the ground. At the end of the straights you can see the tire compress and flatten under braking.

If you ever wonder why the outside shoulders get worn out so quickly, just have a look at what the tire is put through in the tight right hand hairpin... Consider that my car has negative 3.8 degrees of camber, imagine a car with stock alignment.
Now you know why it's a good idea to put extra air in a street tire on a stock car!

Sound is not so good, you might want to turn the speakers down.



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I used this elCheapo $40 security camera

Sticky Monsters

I finally got the chance to try the crack that are a new set of Kumho V710 at the track. BadBadM had described the experience in this previous post but I don't think I was fully prepared. Simply put, I could place the car anywhere, I could take any line I could get away with ridiculous slip angles... it was quite a "different" experience. Well maybe more like turning your amp up to 11.
Even with the a full track and no full laps that were 100% traffic free I was able to turn a lap at better than a second and a half faster than I had previously run at Pocono North during a Time Trial. That Pocono North is made up in large part by a superspeedway section only highlights the efficiency of these tires in the turns.


I ran on them for 40 minutes with badbadM in the car with me so with extra weight (albeit extra weight who was spurring me on with glee)

BBM and I were attending an instructor training school so we literally had no time to even turn the cameras on but I did record the session with the Traqmate.
Best I could do is film the Traqview software on the computer screen. It's not much but you can see some of the functions. In this clip I combined my best lap with Stee's best last time he was there. I'm the blue dot in the s54 MCoupe and Stee is red in the e46 m3. You can see how since I've changed the final drive ratio to 3.46 the two cars are very closely matched with any advantage being due to line and tire grip related bravery (stee was on toyo Ra1 at the time).


Download


you can download the Traqmate file HERE
and you can download the free software on the Traqmate site
Photos courtesy of TrackTime Photos

Kumho v710, Tire of the Undead!

Seriously, you can't kill the damn things. I think of Adil's set of Hoosier ARS05 that corded in 16 runs.... this set of v710 lasted me all of last (2005)season, many times with two drivers.
They must have 150 runs minimum so when I decided to get my lazy ass out of bed on a Saturday to go to an autocross near my house, I never imagined they would have anything more than the traction equivalent of a shopping cart wheel.
But no, the Tire of the Undead just won't die, it worked in the wet and it worked in the dry... I'm sure they were much faster in the first 30 runs but there is still plenty of rubber on them. I guess I will try and kill them at a track event later this year.
Kumho, the choice of the fast and the cheap!

Here is a run in the wet, plenty of oversteer and arm waiving.


Click to download

and here is a run in the dry and fast time of day, as neat as I could make it with the MCoupe.


Click to download

Kumho V710 in real-life use at the race track...

Shop for KUMHO tires at Tire Rack.

If you spend time in the autocross community, you’ve likely had experience with (or at least exposure to) Kumho’s V710 DOT-legal competition tire. With a treadwear rating of 30 and basically no tread pattern (two tiny grooves don’t count as a “pattern”), the V710 puts down tremendous grip. It has nicely-rounded shoulders to help camber-challenged cars (Tire Rack calls this “an inflated shape”), and it manages temperatures pretty well. Users tell me the V710 has a clearly-defined life term… that it simply “goes dead” after a certain number of heat cycles. Naturally, the number of heat cycles seems to vary, depending on who’s telling.

So, what happens when you reassign the V710 to road course duty? It wasn’t my plan from the start… I bought V710s in size 205/50/15, planning for a full season of autocross (averaging 2 events per month), and I intended to keep using Falken Azenis on the road courses. But my Azenis tires died and I wasn’t sure when the new ones were coming out, so I began to wonder if I could “get away with” using the V710s at an upcoming GVC-BMWCCA school at Watkins Glen.

I showed up at the Glen and it was wet, so I left crummy Dunlop 195/65/14 street tires mounted, thinking they’d be the smarter choice on a wet track. Besides, I’d never had this car on a road course before, and wanted to shake it out gradually. After a half-session in the morning, my instructor was whining about the Dunlops in an admonishing tone. “If you brought stickier tires, just put them on the car” he says. “OK, I’ve got some stickier tires for ya Buddy” was my only thought.

So I bolted on the V710s.

Holy cow. That’s a lot of grip! We’re talking about brand-new, green-as-they-get R-compounds, but they stuck like dog poop to a hardwood floor. Soon my instructor and I were trying to sort the chassis, knowing I’d never be able to fully utilize the V710s on a 325i with only springs, shocks, and camber-correction mounts. On this 55-degree day, they didn’t overheat, but they overpowered my brakes! Lockup and ABS activity during trail-braking became things of the past. After that Glen event, I added a larger front swaybar and fixed camber plates from Ireland Engineering, along with Hawk HT10 front pads (www.essexparts.com). Next came a VSR roll bar with Deist 6-point harnesses (www.stableenergies.com). These modifications were done solely to make better use of the grip offered by the V710s. For me it was certain: these tires needed to stay on the car for road-course events.

But would they last?

My car weighs 2600-2650 lbs with driver. I’d like to think this is light-duty for the V710s, considering some of the heavy-car applications I’ve seen in autocross. The V710s have lasted an entire season of road course driving. For me, this season included 6 days at Watkins Glen, 2 days at VIR, 2 days at Pocono North, and a day at Lime Rock. I didn’t use my V710s for autocross this year (mainly because I drove other people’s cars on V710s in autocross). At this season’s conclusion, there is still measurable tread-depth on each of the four tires. I used a very careful rotation schedule to ensure even wear.

How perfect are they?

Of course they’ll overheat when you screw up on a hot day (I’m thinking of this summer at VIR). The V710s will comfortably carry ridiculous slip angles for as long as you like, but as in autocross, the driver must remain conscientious of the rapid temperature build-up this causes. Drive with the tail tucked in, however, and it’s hard to fault these tires. So while you don’t look like Tiff Needel when making laps, your friends in traffic are amazed at the speed you carry into (and through) the corners. I even learned to love the V710s in the wet during a rainy session at Pocono North. On wet track surface, but without “standing water,” the grip was astounding… a couple of autocrossers have reported similar findings. Oh, and be sure to trim down those ludicrous slip angles when it rains.