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Tires advice for my Cobra
(16 posts, started )
Tires advice for my Cobra
I've been getting conflicting advice, and well, I know there are "real" racers here, so I'm hoping someone can tell me what I should shoot for, and I'll give a brief description of how my car handles with the last two type tires I've used.

Right now I'm running Pirelli P Zero Neros, and I also run a set of BF Goodrich g-Force Super SPort A/S, they're both great, but, in some ways I prefer the Pirelli P Zero Neros, although everyone tells me the BF's are better...

Okay, with the BF tires, I get amazing traction turning in, incredible understeer performance, but they can't seem to handle the power, whereas, the Pirelli's have serious understeer problems, but they held the rear end down like it was glued, even on my race tune, just incredible.... Dumb as it sounds, I've considered putting a set of the Pirelli's on the back, and the BF's on the front, but I'd hate to have missmatching tires. Money is no issue, I put less than 2500 miles per year on the car, so whatever I get will last, also I don't spin the tires, it's pointless, egotystical, and wasteful. Can ANYONE give me some advice. I already have a good racing suspension, adjustable ride height and dampers, and had it set up by some guys in new jersey, actually a Porsche shop. (My friend does very basic work there and recommended them to setup the suspension)
Now, does this sound like maybe my suspension is the issue, or it's really just the tires, honestly, in all my experience(mostly drag racing, but gave it up and have been circuit racing for about 6 months I guess, maybe 12 trips to the track, but only the last few times did I truly push the car) At first I was scared, it's not like LFS, you can't see very well, and it's hard to judge what speed for each corner, although I've got it memorized now. But these tire issues are really upsetting me. Nothing scares me more than my rear end coming out to play at over 80mph, or even more. If I lost my car I'd be ....god I can't imagine.

When I'm on the street tune, which as of now is only around 480-495RWHP, depending on weather, both sets of tires are just fine, except launching off the line, but on the high octane fuel and race tune (Est. 600RWHP / Very modest for my KB 2.2 actually, but I want my engine to last a long time) both sets of tires just suck. Is it possible it's not the tires, and it's just that 600RWHP is too much for "any" tire to handle? I mean the tires are huge, I dunno what else I could do. If I take off wot, on the street tune it'll spin through 4th gear, but only slightly in 4th, with the BF's even 4th gear spins like it's first...it sucks.

Can anyone recommend a strategy, or a better tire. I'm already using as wide a tire as possible in the back, the pirelli tire I'm using 275/35ZR20, which is what's on the car now. I feel more confident, and the car launches amazingly well(With tons of practice, when I first installed the Kenne Bell Blower I couldn't launch right, it would just spin like crazy), just let the clutch go at around 2200-2400 and I'm hitting the redline in an instant. With the BF's I get wheel spin no matter how I launch, in fact it's so bad, even if I'm cruising at 45mph in second gear at around 3500rpm, and I stomp on the throttle(on the street tune too) the tires break lose and I hit the rev limiter immidietely.

Can anyone help me out, are these two tires even the best, or have I gotten bad advise. I guess what's most important is keeping the rear end planted, for those of you not familiar with the '04 Terminator Cobra, i'ts unlike all other mustangs, it doesn't have an old school live axle, it has an independent rear suspension, which is great except for a little wheel hop every now and then. Just thought that might be important to mention, cause a live axle mustang is an entirely different beast, my 99GT, even with a good suspension is "nothing" like my Cobra, hell even the Cobra all stock handled nearly as good as the GT did with a $1800 suspension. Live axle only good for drag racing, otherwise worthless, no damn tires help that car.

Sorry for such a long post, I'm just getting really frustrated trying to find a tire with more balance. If ya need anymore specs on the car just lemme know. I really hope someone has experience with this. Oh btw, both tires are amazing well at very very high speeds, as in 160+, car feels extremely extremely tight and responsive. (I don't do this daily plz don't jump on me for mentioning it, plus it was done safely)
#2 - ajp71
If you're after performance and haven't got budget issues there's no reason not to go for semi-slick tyres, their performance in the wet is a lot better than people will have you believe whilst they're not ideal there are a lot of club racers who race on them in all conditions so they make a perfectly good road tyre for anything other than winter conditions. The semi-slicks that I have experience with are Yokohama A048Rs and Toyo R888 Proxies (GG - hard compound), the Yokohamas are stiffer and stickier than the Toyos but won't last as long, the Toyos make a better road tyre and perform much better in snow and ice should you happen to be caught in it than the A048Rs. These tyres are not cheap though, part worn slicks are usually available from somewhere for the cost of budget road tyres, they're probably a good option but you'll obviously need a second set for wet weather/road use.

Tyres will have different behaviour under lateral and longitudinal loads mismatching compounds/types isn't unheard of in racing and if you can find something that works go for it, obviously if you're really going on a blind guess you'll have to be careful at first finding out the finer details of your new setup. The chances are a good matching set will be better than mismatching less good tyres though.
Quote from DHRammstein : also I don't spin the tires, it's pointless, egotystical, and wasteful.

Really?! Points at avatar...
Well thanks for the advice, I overheard someone in my club say something very similar, and well, it looks like I have no choice. As far as winter, the car will be garaged, and only driven on nice days just to keep her nice and fresh.(In my experience, with every ford I've owned, they don't like sitting more than a month)

And yeah I guess miss matching would be a bad idea, besides my car buddies would laugh, not that I care, but most ppl are all about looks, and buy expensive parts and have no idea what tuning and racing are about. In fact, I don't know one person besides myself that can heal & toe....Thankfully the T56 trannies in these terminators are as strong as they are(can handle 850lbs torque, and uber extreme syncros)
I wanna be able to throw the car into corners like I do my 99GT, but that car is so easy to drive, so predictable, only like 375HP with a live axle, as long as you're on even pavement you're good.

Oh the Avatar, that's ironic, that's not my car, just a popular avatar I found on google images. My car is fairly identical looking though. Come to think of it that avatar is gettin old, I'm gonna throw up something new, maybe I can shrink down a pic of my cobra or my GT. My Cobra has the stock wheels on it right now for winter, and no recent pics, so I'll prob put a pic of the GT, or my VR6.

Anyways, ajp71, do you recommend those brand tires for an american car? Regardless I'm gonna start looking into it, and I'm gonna call my buddy, the dude that owns the shop that built a lot of VW VR6, he raced for years, dunno why I didn't think of that. But I also figure this place would be a good start too, there "must" be a lot of real racers/tuners around here, with pretty badass street cars of their own.

Edit: Here, at 0:55 to about 1:05 is a perfect example of the traction problems I'm having, this car is very similar to mine, just different color, I dunno what modds, but it sounds exactly like my car, so must have Bassani exhaust. Imagine that kind of traction problem, but through third gear like mine, his troubles were only thru second gear. Yeah I know the guy's a moron and drives like an ass on a public road.. http://www.youtube.com/watch?v ... RVtAY&feature=related

I just sent a message to this guy( http://www.youtube.com/watch?v ... unHQQ&feature=related ) asking what tires he's using, he has the same year car, same supercharger, etc etc, I'll see what he says and compare to what any of you suggest. Only thing is, while this car hooks up real good, he's just goin in a straight line, I need corner burning abilities.

In the meantime anyone else have any suggestions? I'm going crazy not being able to find a proper tire, I have a feeling what ajp71 suggested is my only option. I can use my stock wheels/tires for winter so no big deal.
For the power you are putting down, what ajp71 said is pretty much it.

semi slicks are the way to go, at least if you are confined to 275 wide tires anyway.

It's definately not your suspension, 275 tires are a bit narrow for 600whp. for that kind of power 325/30ZR20s are probably the minimum you should have if you expect to be able to put that power down at reasoable timing comming out of a turn. That size would just about match your current fronts too.

Unless you plan on changing the rear so you can fit wider tires, you are going to always be limmited on street tires so semi-slicks are the way to go.
I've been considering exactly what you just said. Even my exhaust will have to be redone. Problem is, I've spent too much already, on the damn Kenne Bell charger, so my budget is pretty screwed. Maybe I'll just hold off, throw the BF's back on, sell the Pirelli's, put the money toward making the modds needed to get the 3XX's tires. I dunno why I thought the tires I got would hook up, well, honestly when I had the KB installed, I only expected to use a street tune. But once they did the race tune, just to see what we could max the car out at, it was irresistable, and I had to have the ability lol... I should have considered then that my tires weren't gonna work. Thanks for the advice guys, I hope I an afford to have it done by mid spring, it's a ridiculous investment, but it makes me happy, my car and my son, oh and my PC lol. Can't live without it, and after what I went through last time at the track, there's no damn way I'm running the race tune on the tires I have, although if I can't afford to get the work done, I guess I can go on the street tune, still enough to compete with the majority of cars, plus only 10% of the ppl on the track actually push there cars. (There's always some idiot in a celica or civic or something holding everyone up )
#7 - ajp71
Quote from DHRammstein :
Anyways, ajp71, do you recommend those brand tires for an american car? Regardless I'm gonna start looking into it, and I'm gonna call my buddy, the dude that owns the shop that built a lot of VW VR6, he raced for years, dunno why I didn't think of that. But I also figure this place would be a good start too, there "must" be a lot of real racers/tuners around here, with pretty badass street cars of their own.

Your car should have been setup to suit performance radial tyres, anything should work fine on your car, just get the harder compounds of these tyres if you want them to last on a heavy car.

Quote from DragonCommando :
semi slicks are the way to go, at least if you are confined to 275 wide tires anyway.

It's definately not your suspension, 275 tires are a bit narrow for 600whp. for that kind of power 325/30ZR20s are probably the minimum you should have if you expect to be able to put that power down at reasoable timing comming out of a turn. That size would just about match your current fronts too.

Unless you plan on changing the rear so you can fit wider tires, you are going to always be limmited on street tires so semi-slicks are the way to go.

275 tyres are not narrow by any means, you can get slicks, semi-slicks, premium road tyres, cheap rubbish and any other shape and size of tyre in this size. You might want to go a bit wider but it's certainly not the end of the world. The run of the mill semi-slicks do not come in particularly wide sizes but there are plenty as narrow as you like. 20" wheels are not necessary, will increase unsprung mass, likely adversely effect the handling and limit tyre choice.
I was simply stating that without going to semi-slicks, that was a bit narrow for 600whp. With semi-slicks that should do fine, but wider is always going to be better to a certain point.

Ajp is right about the 20s, 20in wheels are a bit over sized. The wheels and tires I would suggest for a road and track car with that kind of power would be 275/35ZR18 fronts if you want to keep the current width and 325/30ZR18 for the rear.

Thats for high performance road tires though, as stated semi-slicks will work nicely on your existing setup. Though even the semi-slicks will benefit from the extra surface area and you will benifit from the lowerd mass all round.
DHR, are you familiar with these guys?

http://www.tracktime4cars.com

They're very closely affiliated with the motorcycle trackday club I ride with, being owned and run by the same guys. There's a woman who drives with them who also owns a Cobra. I've only seen her on a Ninja 250 but I hear she's quick in her Cobra. I don't think she's running anywhere near that power but she might be someone to talk to.
Thanks I'll look into that Forbin. Oh do you know what safety regulations their are? I don't have a roll cage, and I'm not sure I'll ever have one installed, however I do have the recaro's and good harnesses. I know certain drag strips won't let me race because my times are too fast for not having a roll cage, but that's drag racing, hopefully I won't need one for this program, it sounds interesting. For now, what I do is fairly random, I take my Cobra, and my buddy takes his Audi RS6 and we just race ( I woop his ass hehe.)

As for my wheels, I had a set of 18's on it, and the car handled like total SHIT, terrible. What I have now is 20" in the rear and 19" in the front, and it just feels sooo much better, maybe it just works out this way for my particular car. I agree you're probably right about the wheel size issue, on most cars, but this car just needs big wheels, otherwise no matter what I do I get understeer, wheelspin, badly. Only on the race tune though, on the street tune the stock wheels and tires aren't too bad.

I have a friend looking into it for me, he owns a shop in a nearby town, he exclusively builds mustangs, of all variations, so he should know what's best. Problem is, 90% of mustang owners prefer straight line performance, that's not what I want, so when I start talking about how to get a Cobra to turn like a Vette, they just look at me funny, it's pretty annoying really. (Not that I don't like drag racing, at all, I used to drag the 99GT very often)

I had it out today with the stock wheels and tires, not very good tires, and was able to line lock through 4th gear, that's how bad it is, and that's the street tune. I'll let ya's know what my guy Rui says about my setup. He owns a 2000 Cobra R mustang, procharged, soooo sick, very fast track car, so he should have some golden advice. The '00 Cobra R was the one true mustang ever produced stricly for the racetrack.
CAR SAFETY TECH:
- All cars must pass our tech inspection or they will not be accepted for the track.
- Tires must be free of stress cracks and have at least 50% of tread life and no less than 3/32-inch of tread. Performance shaved tires acceptable upon approval.
- Proper air pressure must be checked.
- Wheels must be free of cracks and damage.
- Wheel lug bolts must be set to proper torque specifications.
- Brakes must have at least 50% of original material.
- Steering should not have excessive play.
- Battery terminals must be tight and in good condition. The positive terminal should be covered. The battery must be securely mounted.
- Safety belts must be in good condition and proper working order.
- Spare tires and jacks must be solidly mounted or removed.
- No loose objects are allowed in the interior. Glove compartments should be emptied or locked.
- No oil or fluid leaks.
- Window glass should not be cracked or broken.
- Convertibles will require a roll over device higher than the drivers helmet.
- No SUV's

more info: http://www.tracktime4cars.com/tpm.php?page_id=policies
Great, I'll have absolutely no issues at all, not with the VR6 or Saab either, which I plan to race this summer also.
most of the guys i know who race sports cars use Toyo R compound tires (which are semi-slicks).
after pondering for a bit about the difference in balance you experience between the BFG's and the Pirelli's, i think it might be a temperature issue which can be resolved by experimenting with the tire pressures.

i'm guessing that either one end is running warmer than the other, and the tires have different sweet spots for temp, which happen to give the BFG's a lot of grip at whatever temp your fronts are running and the Pirelli's a lot of grip at whatever temp your rears are running, OR, it's also possible that the differing sidewall construction of the tires is causing one to be more sensitive to the extra camber in the front.

either way, i'd suggest you get a pyrometer (if you don't already have one) and measure your tire temps under as controlled conditions as you can, then use those as a guide to adjust your tire pressures towards the balance you want.
You really ought to be on DOT R-compound tires. The difference between these and a true street tire is amazing. There are several brand thst will fit your snake, and others who track mustangs should be able to suggest the correct on for you.
Thanks a lot guys, good advise. My man Rui says that my BF's are a much better tire than the Pirelli's, I dunno but he's like a genius. He also told me 20"rear and 19" front is a little big, even tho it works with my suspension, he recommended the same size you guys are, 325's, on an 18" wheel. So I'm gonna use my stock wheels for now until I sell my others. The reason I had such a large wheels is I had them staggered, it looks really sick, but looks aren't my goal, hell from the outside my car looks entirely stock, except the exhaust in the rear.

When the tires come I'll take the car to my local speedshop, I need an oil change anyways and they're the only one's who carry Royal Purple. I'll let ya's know how it handles.
He also said if it doesn't feel right with the 18's he's gonna drive the car himself to make sure it's not me having a problem, and if not, he'll start working on the car to get it right.

Thanks again guys.

Tires advice for my Cobra
(16 posts, started )
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