Wow. Truth in advertising, what's that?

 

This is the first I've heard of the 255/275 carcass sizing info -- would be very useful, and I might ultimately go that route.

According to the TireRack data, the 255/40-18 isn't the same width as the 255/35-18, so I'm assuming the 35 and 40 series tires are two entirely different molds? The two inch height reduction of the 35 series tires is pretty significant compared to the less than one inch change for the 40 series.

http://www.tirerack.com/tires/tires....r&tireModel=R6

 

Just going by specs - yes these tires are quite different.

From Hoosier's site and the tire rack's site, there's another anomaly:
The 285/30-18 has a tread width of 10.9", while the 295/30 is 10.8" and the 295/40 is 10.5" (which is only .2" wider than the 10.3" 255/35-18)

I'm now considering going with R6's 255/35-18 for the front and 285/30-18 for the rear - this gets the tire diameters very close (24.8" front 24.9" rear).

 

The only caution is those tire heights are over 2" shorter than stock. Depending on the track, you could run out of gear and have to upshift more often, or hit the top speed limiter if it's a very high speed track.

 

Which begs the question is Track Key going to remove the speed limiter. Not that you ever want to have to shift to 6th on the track as 6th is a super overdrive.

Peter

 

double post.....

 

I'm going to say it doesn't remove it. I think the speed limiter is set to the lowest common denominator for parts engineered to a certain speed. I was told specifically that is the driveshaft, but haven't been able to confirm that directly from Ford. There are numerous parts that have to be engineered to withstand the rigors of high speed driving and the limiter is set accordingly.

Who knows what all needs to be upgraded to achieve an acceptable failure rate for a production vehicle at speeds over 165. For example, a Super Snake was trying to hit 200 at the Texas Mile and despite numerous upgrades, a part that failed at 194 mph was the A/C compressor. They did a pulley delete and then the trans failed.

 

I thought the Boss speed limiter was 155.

Peter

 

So did I, but myself and others have run it past there.....at least on the stock speedo (which reads high). True test is to get somewhere where I can do it with the GPS, but I haven't had an opportunity. I have hit 150 at BIR but run out of track. Airport or Texas Mile anyone???

 

Or the Mojave Mile... I might run the MM next Spring but I don't expect to exceed 155 in a standing mile. Stock Z06's are getting close to 170 with a good launch but our Boss cars are aerodynamic bricks.

 

You're right it will take more than a mile I think. The front straight at BIR is about a mile long and you probably come out of Turn 10 at 50-60. That said, you do lift before heading into Turn 1 so you don't get the full runout

 

Square because you can rotate them--tires are my #1 expense for any track season.

I felt that an adjustable rear bar was needed for a square setup.

 

Yeah I am sort of looking at Brainerd Turn 1 with a little as I get to run it in the 2012 OLOA with only a course walk and warmup lap. I think it will separate the men from the boys or otherwise who has the biggest Man Bearings.

Peter

 

http://www.trackpedia.com/wiki/Brain...tional_Raceway

 

It does. I'm just not smart enough to back off. I usually pick up quite a gap there between me and the car behind me. The trick is getting the car to "set" before turning in. There are a couple of slight bumps and when it "sets" on the second bump I turn in and go. I put my right tires just below the seam where they poured the new surface at the bottom of the turn. You should hit 150 before lifting, bleed off to around 120-130 and if you're flat footing it from the apex, hit 140 on exit. Turn 2 is the bigger pucker factor though since there's no banking and the surface is pretty rough. Brake a little harder than the other cars and turn in at about 110. You can be flat footed on the throttle at apex and exit at 130 which is faster than just trail braking in at 120. Oh and by the way, don't look at the trees because there isn't enough runoff to bleed off 130 mph in a 3600 lb car.

 

Here's a good turn by turn description. I particularly like their description of Turn 9 under the bridge

http://www.brainerdraceway.com/track...scription.html

 

Interesting. I was turning 1:52s this summer with a fast lap (unofficial) of 1:50.6. There was a guy running stop watch between 3 & 4 who had me at 1:50.6. During that lap I caught a 944 between Turn 3 & 4 that was driving like he was in the mall parking lot. My start/finish was set between 5 & 6 because it gave me the most consistent read, and I still hit 1:52.3 after following him at half speed through 2 turns, so I'd say the 1:50x was believable. Will be fun to try again next spring with TracKey and Hoosiers.

 

Yeah I have watched some video and saw how rough it is going into turn 2. Video is good but you don't get to see the banking in turn 1 just like video of HPR doesn't give you a good feel of the elevation changes. Thanks for the description of turns 1 thru 3.

Peter

 

I saw 155 on the front straight at Daytona.

Ted from TMS Motorsports with his Boss, tune, long tubes, air intake calimed 170ish on the front straight at Daytona.

 

Unless it was on GPS I would say it's suspect. My speedometer reads over 160 when my true speed is 150. Mfrs set the speedos high from the factory and it might be 2-3 mph at 70 but significantly further off at 150.