Would like some opinions regarding tire widths for the track:

I currently run 275/40/17 Nitto NT-01s on 17x10s all
around and love the setup/grip, but was thinking of moving up to
Hoosier R6s in the same size for NASA Time Trials (TTC).

BUT a couple of local Z drivers have experienced being faster on 255s
vs 275s. This doesn't really make sense to me, I think wider is better,
specially since 275s are not super huge and would provide better grip,
right? But the lap times don't lie, if 255s are faster then thats that.

Just want to see if anyone has had the same experience or maybe an explanation
as to why that is the case, before I move to the Hoosiers.

Thanks

 

Did they run on the same day? Temp is a big variable.

 

Cant speak for 17s Leo, but my times improved going from 275/35/18 R6s to 255/35/18 R6s. The thing about hoosiers is that they are wider than different brands of the same size. A 255 Hoosier will be just as wide as your 275 Nitto. You can have too much tire. If you the increase the grip with width but it causes you to scrub off too much speed, tires get hotter, corner exit speed is lower, etc. and you are worse off than you were.

Either way, go Hoosier with NASA. When you get competitive, though TTC is dominated by Victor Leo in a boosted 99' Miata, you can win free tires.

275/35/18 R6 - tread width 10.3", diameter 25.5"
255/35/18 R6 - tread width 10.3", diameter 24.8"

That .7" decrease in diameter is about 2.7% which improves my gearing from a 3.9 to a 4.05. Not significant, but I can feel it.

 

Can you run the 285/30 R6? I have been for awhile now, and am hooked. They run big like the 255, 10.9" tread width = noticeable, and only 24.9" tall, just over the 255/35. I tried the 295/30s, but similar to the 255/275 comparison, they aren't any wider (actually 0.1" more narrow), but 0.4" taller.

 

He is going to campaign his Z in TTC, which only gives him 19 points. The base width is 255mm. Running a 285mm would be +7. The Hoosiers themselves are +10. So he would have 2 points left. Not the best use of points.

 

Yeah, I see, seems that for 18s the 255s are a win-win, same width less TT classification
points.

For the 17s, the difference is .6":
<pre>Tire Size Tread Width Rec. Rim Meas. Rim Section Width
P255/45ZR17 9.7" 8-9.5" 9.0" 10.8"
P275/40ZR17 10.3" 9-11" 9.5" 11.0"</pre>

Based on your info, for my particular case running 17s may be a disadvantage. Your rims are 9" wide right?

I wonder if I can even run 255s on my 17x10s, the recommended rim width for the 255s is 8-9.5"......damn.

 

285s would require too many points and would bump me to TTB, woud like to stay in TTC. I bet the grip w/ 285s is awesome though!

 

I spoke w/ Ernesto @ HMS this past weekend and I believe he got his car reclassed by power/wt....he ended up in TTD**! I don't know if its official, will have to wait and see, BUT, if that is the case, the Z will get an extra 5pts (24pts total) and still stay in TTC, I hope he wasn't kidding......this would make the Z VERY competitive!

 

You gotta do the points out both ways. Its what I did but I had a ton of mods to my engine during my build that give me any power but were still points. I was reclassed to TTB*. The winnning times for TTC is a boosted Miata that turns 2:28 at Sebring and 1:42 at HMS, a winning Z is gonna be tough. But I see he isnt registered so the Zs have a shot that weekend, see you there!

I have 9.5" wide wheels all around.

 

Spec350z FTW!

Florida region is blessed w/ some damn good drivers (a few Nat Champs in a bunch of classes) so its tough, makes it even more fun though. We'll see how things shake out.

The Sering times though are just unreachable, unf'ing believable.

But I'm running 1.45s at HMS, by my estimates (maybe overly optimistic), there is time to be gained by the following:

LSD = -.5 sec (OS Giken seems to be the winner here, my stock VLSD is over 100k miles old)
Hoosiers = -1 sec
Driver Mod = -.5 sec
Suspension upgrade = -.5 sec (need to decide, thinking about going from Koni SA to Unitech Phase IV coilovers)

With 2.5secs that'd be in the ballpark, only time will tell. Then again Victor an Ian are just INSANELY fast (other drivers too), they probably have tricks up their sleeves too. Can't wait to get back out there.

 

I've always found that Nitto tires fit more "narrow" than other tires. I also run 275/40/17 NT-01 all around.

I should measure the differnce, I have a set of Hoosiers and NT01's sitting at home, "same size"

 

Exactly! Tire compound is more important then tire width and Hoosier always understates their actual tire width. It also depends on how fast the track is. At the Cal Speedway Roval my 350Z will turn a quicker lap time running on 255s then with 285s on equal tires. Its because so much time is spent running over 120mph on the NASCAR front straight, turns 1 and 2, and infield backstraight that any aero and tire scrub advantage helps.

 

What size rim are you running?

 

^ 18x9.5 Enkei RPF1 all around

 

The +15s I assume?

 

Yes sir, fit great. It was the shops recommendation. Pretty bad that after 5 years of track experience that I dont know about offsets lol.

 

It doesn't hurt a 255 is also about 1-2 lbs. lighter per tire. However, depending on the track its possible balance is more important than overall grip. So if you are generating 1.08 (lateral grip) with 275's and 1.02 with 255's if your on a track that rewards the balance more than overall grip, the 255's might be faster. But I think the racers and avid track guys may agree with the fact the larger tire will likely handle the heat better than the smaller tire. Generally smaller tires on a relatively big and powerful car tend to overheat quicker.

 

I figured so. I had a local guy get the same set, and his car rubbed with 275/35 tires. The 285/30 would have likely been better since it's a shorter tire, but just a heads up.