dmoffitt

iTrader: (4)

(and that contributes to this thread... how?)

that size is grossly small for a Z - if my "oem" sized fronts were 245/40/18 you're over an inch small on the OD. not good.

mikhe

like i said, i was just suggesting something IMO.　since alot of more experieced track racer here with alot more track record suggest otherwise i:ll take back what i said. What i was more amuse here is the tone and attuitude here lately with some people lately. It:s like i said something that personally offended them by stating something wrong ( not OVERLY wrong in my book ).

well anyways im out of here

tmak26b

and? the car looks like it is riding on 4 flat tires, but it sure does go. I am sure I can pick up a little more time if I went with 245/45/17 or even 255/40/17, but then I still have to give the 235 credits for getting me some quick lap times. I am sure I can run with you on 235s than you on whatever

Kolia

iTrader: (2)

tmak26b is using r compound tires. That will affect the end result...

betamotorsports

iTrader: (1)

A smaller tire OD can be a good thing. Depending on the affect on gearing it can move a shift point on the track from a very awkward spot (turn 6 a WSIR is one of those places) to a more safe shift point. It also improves acceelration in lower gears and can reduce MOI. On my car going from the factory 40/45s to 35s reduced the tire OD and helped second gear at a autocrosses but hurt lap times on the track. Going back to 40s helped on the track but hurt second gear during an autocross.

scotts300

iTrader: (46)

Why haven't you put 275 RA1s on your track set-up?

If I must "qualify" myself, I'm happy to do so.
I have over 5000 seat miles, combined, in my Z32 and Z33 (and a few in my Mini Cooper S) in open road course (HPDE) events, which equates to approximately 50 track days.
This is also my 6th season of autox, also in both cars. I am certainly more an open track guy than an autox-er.

I have been an instructor in various groups at Thunderhill Raceway, in Willows, CA, and plan to drive my Z32 in the Redline Time Attack at Laguna Seca this November.

I will admit that I have NOT put tires on wheels larger than the recommended sizes, however, logic indicates that a tire too large for the wheel would add to sidewall flex, even if you feel it "works fine". What is the point of no return? Can you put a 315 on a bicycle wheel? Of course not, but somewhere in the middle, which is where I firmly believe you are, the extra contact patch area will not be worth the added bulge and sidewall flex that the oversized tire brings. Some tires are sidewall reinforced (like some sizes in the RT615-series), so if you choose one of these tires, the sidewall flex may be more minimal; I have not tried this either.

I have stuck within the guidelines of tire manufacturers because a) they are so for a reason, and b) that is what my instructors taught me years ago. This coming from amateur pro-racers, SCCA competitors, Skip Barber graduates, etc. I'll take their guidance over any "I have not had any issues" forum comments any day.

Thanks for understanding my POV as well.

..... Laguna Seca corkscrew ................Thunderhill 5B..... .............Thunderhill 9-10.........

daveh

iTrader: (9)

I'll add my real world experience to this thread. I ran two seasons on 275 RA1's and had to switch to a narrower 255's this season do to rule changes. I will say that there is much more to consider than ultimate grip in a tire. My lap times didn't change all that much when I downsized.

Things to consider:
The shorter sidewall of the 255 has less flex than the 275's and offered better steering response and less tramlining. The 255's made the car car feel lighter on it's feet and more nimble. They weigh something like 3 lbs less too.

The shorter sidewall acted like a free final drive (only helpful on some tracks though)

All in all, I might be happier with the 255's. It's more of a seat of the pants thing as I like the quicker reflexes over the 275 RA1's. Perhaps using a tire with a stiffer sidewall would help..

scotts300

iTrader: (46)

Thanks for your inputs, Dave - I was hoping you would chime in. Z-ya at the track sometime!

l30thelion

iTrader: (3)

I think the question that I am asking has been answered, but to be specific:

I run 275/40/17 V710s on stock wheels (17x7.5 & 17x8) for autox and they worked great....could I safely run this setup at HPDEs/TimeTrials, or should I consider other wheels sizes due to safety?

Thanks!

scotts300

iTrader: (46)

V710s are not a tire for HPDEs. Since you'll be buying new tires anyway, I SUGGEST you get tires that fall within the tire manufacturers recommended sizings. I have separate wheels and tires for autox vs track as well.

tmak26b

I personally stay away from 255s because I have 7.5" in the front. While you can get bigger tires to fit, but I never like the idea of stretching a tire. I would much prefer to have a tire that fits right than to force something in there when I am pushing the car hard on the track where there is not much margin of error. The later cars have wider wheels, so 255s might be an ideal size. I think 245 is the best for people iwth stock 17s.

People have used V710s for the track, they just won't last very long. I was effective for 3 autox on my V710s. After the initial mojo, I found them to be similar to the RA1s I am using.

dmoffitt

iTrader: (4)

Whether you can or not (I won't bench race or speculate, I really don't care) that's a pretty lame response. Really? You're faster than me? Wow, I didn't know we were racing. I was trying to learn (and feel that I HAVE learned) a bit more about tire sizes / selections for my car. In order to better learn to driver it. In order to have fun, improve my skills. I don't quite see where in there I said "I am faster than you, we should race" - sure, ok Vin D. You can take your 10 seconds-at-a-time and shove them up ... well, you get the point.

I was merely pointing out that that's an awfully small OD and rather narrow section-width. I'm sure you have PLENTY of reasons for choosing it, but I do feel I was correct in saying "so what" - heck you can fit 235s under all 4 corners of a Civic - so it's not exactly earth shattering nor answering the questions at hand (besides it being a square setup). You didn't have to go of on me like a real a-hole. Truly uncalled for. You might be tallented, and a great driver, and god's gift to racing, *shrugs*, you might be my next instructor (god, I hope not) but it doesn't give you the right to "talk smack" as some might say.

/rant

Back (somewhat) on topic, I presume you're running those widths because of some sort of classing or regulations you're trying to stay within (or because of budgetary concerns, or sponsorship, or who knows?) - I'd be curious if you could elaborate on the V710 vs RA1 in your experience, as from what I hear, "the RA1 lasts the longest, and sucks the whole time" (from my friend's father who instructs with PCA / BMWCCA and other groups and much preferred other tires over the Toyo)... or is there another take on it? My understanding - DISCLAIMER: from talking to a lot of people, not from my own experience yet - is that the Hoosiers have the most grip but lose it the fastest and only last a few cycles, the Kumho is an excellent value in that it has pretty darned good grip but also obviously doesn't last forever, and that the Toyo is mediocre (but still far superior to street compounds) but lasts considerably longer / doesn't necessarily decline in performance as quickly.

That said, I figured I'd stick with street tires for at least another year/season or two of DEs and other events since I'm not competing and would rather not mask driver error with enhanced grip / wanted to keep the limits a big lower in order to explore them a bit more without having to push things quite as hard. Good idea? You tell me... you've clearly positioned yourself as a far more experienced than me (sorry, had to get one last little jibe in hehe).

tmak26b

You are the one that was quick in writting off the 235s. I was simply stating that it is a perfectly good setup, people should not shy away from it just because it seems weird. Everyone drives different (well maybe except BMW drivers, they are like robots), you get whatever that fits your driving style. The difference between 235/245/255/275 isn't worth more than a second or two, get whatever you are comfortable with. If you truly want to learn about improving your skills, go out and drive, not worrying about car setup. Sorry to be so blunt, but that's the truth. Nothing beats practice....

V710 is EXTREMELY fast for 500 miles, then they are only good for 1500-2000 miles. RA-1 is good for 5000 miles roughly. You give up a little grip for a lot more longetivity. If you are not comfortable with race tires, you should not get V710s. You will just be wasting your money as you will lose the very good stuff very quickly. I say a V710 is worth another second to 1.5 sec over the RA1 when they are new, even when they have a little wear on it.

Kolia

iTrader: (2)

I personally would be extremely weary of anybody using these type of adjectives to describe a well established race tire. This is an empty statement meant to attract attention to one's self in order to compensate from a lack of love from their parents...

The Toyo RA1 tire might not be the fastest race tire, but it's definitely an excellent DE tire as it can be used in any condition (dry or wet), it's predictable, runs in a wide temperature range and will last long enough for you to learn it's characteristics.

Driving style and personal preferences have a large impact on finding a tire that works best for you. Yes, the Hoosier are faster, possibly the V710 too. But read a bit on tire maintenance and break-in procedures. You'll get a better appreciation for the "slap-on drive off" qualities of the RA1...

tmak26b's point on using relatively narrow tires is a valid one. It allows him to have a stable tire that last a full lapping session and at the same time he can play in the slip angle zone more easily, at slightly lower speed and with better control from the reduced side wall flex. This is how he likes to drive and honestly, threading the limit is the whole point of going to the track.

Let's calm down on real or perceived offensive comments and let's back on topic.

Cheers!

dmoffitt

iTrader: (4)

That was my whole point as well. As an admitted n00b, is there a benefit to be on a narrow r-compound vs a "normal" sized street tire? I say normal because it's what was recommended for a 9.5" wheel, aka I didn't use a "racers trick" like John/Beta was saying many people have done to fit a non-standard size. I would guess / answer my own question with "the r-comp will last longer / not chunk up like a full tread depth street tire could" - but on the flip side, I got a TON of life out of my PS2s with numerous weekends - only reason I got rid of them is I sliced one up pretty badly during an "off" earlier this summer and had worn out the rears so I said "Why not try the new RE050A PPs" - figuring eventually I'll want a set of street/rain tires for wet DEs and a set of "faster" tires for dry days.

I'm just learning / only interested in DE for the moment if that helps qualify my perspective and experience. I'm a technical person and consider myself a good learner, but have a VERY long way to go.

I was merely "shocked" at how small a tire that was diameter wise - I wasn't meaning to "write it of" as you say.

tmak26b

Kolia is absolutely right on. With stock power and stock wheels, I don't think anything over 255 (or even 245 due to the 7.5F rim) are useful on the track. The 235 allows me to slip and slide controllablely. It doesn't have the stability like the bigger tires, but it is not a bad setup. That's why I said it is a personal preference, some people likes it and some people don't.

You are right in saying how small the tire is. My car looks like it has four flat tires with the 235/40/17s on, but it works well for me. I will keep using them until I switch to the 245 NT-01. I did have 245 V710, absolutely loved it, but they don't last long at all. Since I go through about 16 tires a year, I decided to go with the used RA1s rather than keep buying new tires. With the lack of camber, you are bound to sign a big check every three months for new tires.