The OEMs are 18's. 225/50/18 front and 245/45/18 rear.

Since Mike and I are asking similar questions I figured I'd ask this here.

I probably need to replace my rears before the next event. Should I go ahead and just get the same size (it's pretty stretched) or spring for maybe a 255-45 or like a 265-40? What kind of size would you guys recommend?

Also - what do y'all (hi from Texas ) think about Sumitomo HTR Z tires? Or what about these http://www.tirerack.com/tires/tires....e1=yes&place=0 - they're on closeout for only $99 bucks

I'm looking for a very reasonably priced tire that will perform well. Obviously comfort and road noise are no issue. Should I look for a higher treadwear rating, or just look for AA traction or what?

Any/All suggestions for a good, reasonably priced track day only tire are appreciated

 

Some great "bang for the buck" tires:

Kumho Ecsta XS
Federal 595 RS-R (RS-R, not R or RS)
Nitto NT-05
Dunlop Z1 Star Spec

These will absolutely blow away the Sumitomo HTRZ (and HTRZIII). However, none of them are very good in the rain....

Lower treadwear = wears faster. Generally, lower treadwear tires are sticker. However, each manufacturer has their on standards, so the numbers can't be compared across brands. The "AA, A, B, C" traction rating is for wet condition stopping; the stickiest summer tires generally only have A or B ratings. All-season and 'high performance' summer tires can have AA ratings.

If you're going to get a dedicated set of track tires, have you considered R-compounds? Keep in mind with R-compounds, you will be able to sustain lateral G forces the car was not designed for, and can potentially cause fatal damage. (Basically, stay away from tracks with banked turns, or long series of slaloms).

Do you know the width of the OEM 18s? I want to be sure before I recommend a size...

 

yeah, i was looking at those Kumhos. However at only 100ish per tire for the Sumitomos I don't think those can be beat at the price point. As long as theyre decent tires, this will only be my second autox event - as I'm hoping to get into the sport now so I figure these will be great starter tires while I'm still learning. Honestly, I'm not looking to be competitive yet, just wanna work on my skills and have some fun.... affordably haha

I saw some R-compounds - what do you mean about gforces the car wasn't designed for? Like the car will somehow "fall apart" or something? Autocross is tons of slalom and the track I plan on going is a Road Course stemming from a banked oval!

18x7.5 and 18x8.5. I have some decent tread left on my fronts so I was hoping to just do rears for now. I PM'd the tire rack guy on here and he seemed to recommend sticking with OEM sizes but his reasoning was mostly about VDC which I would hope wouldn't become an issue while the VDC is "off" (however OFF it actually gets).

 

If it's just an instructional course and not a race, you may get away with it. They didn't inspect my car at all at the EVO autoX instructional event I attended. Having said that, my tires were pretty worn (still had some tread with no wear bars showing) that day and I slid around quite a bit. I was running 245-45-18's and prefered dealing with the oversteer to previous understeer. You may just want to use your other set.

I also started with my VDC on and it sucked. My car would start to slide a little and as I was starting to turn into the skid (drifting a little) the VDC would brake the car HARD and completely throw off everything I was doing. Leave your VDC off and just learn to handle the oversteer. It was a lot of fun that way.

 

There is a world of difference between the Kumhos and Sumitomos. You put premium fuel in your tank right? To give you a real world example, I daily drove on my track tires (Bridgestone RE070/RE01R) for a while. Then I caved and got another set of wheels and put some Bridgestone S02's (OEM tire for last generation porsches) on them. About a week later, I had to do a brisk stop. I set off ABS and didn't stop as quickly as I would have liked. On my track tires, I would have been using maybe 60-70% of the grip available, but I had completely exceeded the limits of these tires. Don't cheap out on tires. You'll LOVE being able to fly around freeway onramps and stop on a dime. Remember, no matter what you do, the tires are the ONLY part of the car that touches the ground. Good brakes, suspension, and power, all can only be put to use if you have traction. (Premium tires, IMO, would be either the Yokohama Advan AD08 or Bridgestone Potenza RE11)

As for R-compounds, they offer more grip than your "performance street tire".

As such, you can brake later and harder (increased brake/suspension wear) and turn harder (increased suspension/chassis wear, potential oil starvation issues).

I can go more in depth about r-comps as you start using them.

I would ask the guys that track a lot at your local track if they have oil starvation and/or blowby issues on the banked turn. Out here in So-Cal, the banked turns are short enough that a simple mod such as a baffled oil pan (and overfilling oil) is enough to protect your engine.

 

I actually use diesel, I was looking for a bit better mid-range torque

These will be track only tires which is why I don't want to have to spend a lot. The Kumho's are like $50 more than the Sumitomo's - maybe if I can find them in sizes I'll "splurge" ha. I won't be looking for R-compounds because A) they're expensive and B) let's admit it, the reason I'll be slow on course is my skill level, not the tires haha. I've already heard it's better when you're first learning to do it on sh!tty tires because then you learn how to catch things better and work your way up to R-compound type stuff. If you only run on great tires, they'll make you feel and look a lot better than you actually are (aka Nissan GT-R).

Well hopefully running street high performance tires I won't have those issues. Yeah, I'll have to ask around if anyone has run into issues up on the banking - I know you only get on the straight while driving the road course which isn't banked nearly as much as the turns (22 degrees).

I'm an admitted novice to the sport, so treat me as such . I'm not really looking to be super competitive, at least not now. I'm looking to gain a lot of experience driving the car, learning it's limits, and #1 to have a lot of fun doing it. Which is why I'm considering a cheap(ish) set of tires to learn on. Then if I really get into tracking/autoxing and get good at handling a car on OK tires, move up to a set that will let me excel.

Yeah, I'm for sure using my OEM extra set even though they're quite worn. The set of wheels I have on now are my daily drivers and those won't be seeing any track use. I was expecting a lot of oversteer as it is ha, and yes obviously the VDC will be off. The first time I did autox was in a '00 528i and in a long 180degree turn I spun and midway through the car decided it knew better than I did and I pretty much had no say on what happens with the gas or the brake haha - accidently left the DTC (dynamic traction control in the germans) on that run.

 

Looking around, I don't think the Kumho XS comes in 245/45-18. Closest is 245/40 - the TireRack guy said i'll run into problems running a shorter sidewall.

 

The shorter sidewall will mess with VDC, if you run the 'standard' size in the front. If both are reduced, then VDC will be okay.

The major effect of having a smaller sidewall is the effect on your gearing. You'll effectively be putting more torque down to the ground, so you'll actually accelerate faster, but your gears will be shorter. Your speedo will be reading higher than you're actually going.


Since these are track only tires, I really recommend you get a good tire. Reason being, if you are doing hot laps, the tires heat up as you're driving, and stickier tires take heat better. All street tires eventually overheat and become greasy (slick), but the 'budget' tires do so much faster. Once the tires overheat, you'll start to experience chunking (litterally what it sounds like, chunks of the tire fly off), and significantly shortens the tire's life. This will be a major issue, since IIRC, most TX tracks get rather hot for most of the year, similar to the tracks I go to.

Also, tires can only take so many heat cycles (getting hot, cooling down). If you get the tires extremely hot, then their lifespan is significantly shortened.

In the end, if you get cheaper tires, you may still have tread on them, but they'll be rock hard.


I'd also recommend purchasing two relatively cheap tools: a tire pressure gauge, and a laser temperature reader. They'll help you adjust your tire pressures so that you can utilize your tires to the max, and possibly help prevent overheating them. I can help you with basic tire pressure setup, but each driver will eventually develop their own preference


Remember, the Sumitomo HTRZ and Kumho Ecsta XS, even using tirerack's catagorization, is 3 groups apart. The HTRZ's have far less grip, even compared to the OEM tires.

 

Mann, I just can't afford to change out all 4 tires with the Kumhos though. If I had the cash I would. Maybe If I go with the Sumi's or try and find a set of used rear OEMs for now and keep the costs pretty cheap while I still get into the sport. I'm planning on much more autocrossing than track days, due to cost and wanting to still build comfort with the car. So I won't have huge issues with the tires building up a lot of heat since there's down time between runs. Down the road if I start getting real serious I could change the tires out then.

If you HAD to pick a $100ish tire to learn on, would the Sumis be an ok compromise or would you recommend anything else?

And thanks a ton, i don't know where I'd be without all you guys on here. Probably a lot richer with a boring *** car

 

Hmmm... you may want to look for some used tires. Occasionally, there are used tires for sale that have only a few heat cycles on them, although I wouldn't know where to tell you to look, since the tire sizes the G uses arn't used on any of the cars I've tracked.

You may actually want to try the FS sections of BMW forums. If you can't afford to spend more than $100/tire, I'd recommend that you keep the tires you currently have, and use them for street driving AND track/AutoX. Heat won't be as much of an issue when you're starting out anyways. Spending the extra 400 for an extra 2-3 days of track time will do a lot more for your driving than going for tires. If anything, you'll want to get brake pads before tires

FWIW, a set of dedicated track r-comps will last me 6-10 track days, including the drive to and from the track.

 

I don't know what the hell I did haha - I found a set of '03 350z wheels for 700 with decent tread left on the bfgoodrich KDW. BTW, I have a set of G37 coupe sport wheels with the OEM tires that are my daily drivers. So at the moment I've got three sets of wheels in my house...

I'm hoping that doing this - then selling my OEMs for a "lowest" offer of 500 I'll have spent 200 bucks for four better tires with a bit more tread on all corners.

Although I'll have completely shot myself in the foot if I can't offload the 18" oems.... took quite a risk on it but we'll see what happens.

Whats your opinion on where I'm at now? haha. the tires are 225-45/18 and 245-45/18 which I'm pretty sure keeps me in the stock autox class due to same width as stock tires. So I lost a grade in the sidewall in the front (and it shows) but I'm really hoping that with the VDC turned off, or at least as off as we can turn it, I won't run into any issues. The car turns in much quicker now, the turn off center comes much quicker, much easier with these tires and I'm attributing it to the sidewall. And all I did was drive around the block to subway and I've noticed they're quite a bit louder, rougher, but turn in better

 

So, to clarify:

You have 18" OEM G35 sport rims with RE050A
You have 19" OEM G37 sport rims with RE050A
You have 18" 350Z wheels with KDW.

Those OEM tires on the G35/37 rims will blow away the performance of the KDW, and all 3 sets will destroy the sumitomos in terms of performance.

Also, IIRC, those rims technically disqualify you from stock class, since it is not litterally "stock" on your car (and even if it is OEM for the car, it must be offered for your year on the car. E.G. my s2k is 08. there were 16" forged wheels available as an option from 2000 to 2003, so I can't use them on my car and stay in A-stock). I don't have much AutoX experience, so I may be wrong.

 

As I stated earlier in the thread, you are still stock as long as the wheels are the stock size. I don't know which are which in the list above, but so long as the height (18") and width (whatever that may be) are the same, you are still stock. There are offset limitations, too, but I won't get into that.

 

My wheel and tire setup is 17x10 +24 FN01RC wheels all around and "used" 275/40/17 Goodyear Eagle RS tires. They have a slight stretch to them so you'll be able to get the feedback you'll need from the front tires. I like them more than the Hoosier tires. I buy all my tires from Bob Woodman Tires, you have to inquire within for used tires he has in inventory. The "used" tires he has are used by teams for test runs with less than 15 minuteson them. Theyre all properly heat cycled and, in my case, lasts a whole year without breaking the bank with new tires.

Here's their link
http://www.bobwoodmantires.com

 

+1

I've ran 3 track days on a 1 race set of Toyo R888's I bought for $350, these tires still way out perform the Hankooks I drive on daily. Find a cheap set of rims and slap on some used R rubber.