I was very happy with 255/50/16's rear and 245/50/16" fronts for hi-performance street use and only changed to a 17" rim to fit bigger brakes. Straight line traction wasn't great thoguh, and probalby would have been a bit better with a wider tire. On a street car, there are a lot of disadvantages to an extremely wide tire with a short, stiff sidewall. OTOH, the wider rubber will help for autocrossing.

Rich Krause

 

Like hydroplaning?

 

That is a good point. You will be more susceptible to hydroplaning with a wider tire because the is just more area that the tire has to push water away from. Tires become a big factor in this aw well.

 

Well, I'm looking for straight line traction, but I want to keep it street legal. Plus I'm afraid that running slicks will blow my rear end out, I don't $2000 right now for a strange 12. Right now I have 17x8.5 with 245/45/17 nitto 555r's. Gained .4 with them, but I'm still having traction problems off the start.

 

Just thinking about getting 17x9.5" replica ZR1 rims. Do you guys think these wheels would have hydroplaning issues? Kumho ZRated tires on them of course - what do you guys think?

I also wanted to go with the Baer Front brake kit for like $600-800 (13.1" rotors and 3-piston calipers - just cut off the stock mounting lip, install brackets with calipers ). Stock LT1 brakes suck big time and I also dont like the thought of having to get my alignment redone with the LS1 brake upgrade...

any thoughts on this are welcome

thanks!

 

As long as you're easy on the throttle, and don't drive in rain with bald tires, it isn't too bad. I don't know about the wet traction abilities of the Kuhmo tires, though.

 

A thinner sidewall does not mean better handling. Just as some ammount of body roll helps our car on the skid pad, so does the flex of the tire's sidewall. The smaller the sidewall the less area there is to flex, that is a given. But the thing that is over looked is the fact that the fast way through a corner is by using the correct slip angle. This is discribed as a felling of a very small mount of push in the car. It actually is a veriance between the tires direction and the acutal direction of the car. This differnce is in one part by skid and another part by the flex within the tire. With a thinner side wall you have a smaller performance envolope for the tire to operate in. This will make it signicatly harder to control the slip angle while also making the car more subseptibale to "coming around on you".

 

Ever look at the tires used in road racing? You will note that they have a higher aspect ratio (sidewall height/width) than many street tires. Does this tell you something? The tiny sidewall/big wheel thing is style statement, not a performance enhancement. I saw a Ford Expedition the other day, lowered probably 5-6 inches with 22" wheels. The sidewall was all of ~2" tall! Really retarded, especially on a "truck". One good pothole or brushing up agianst a curb and bye-bye wheels and tires!

The are numerous advantages to a tire with a taller sidewall, here are some of them. Assumes all else is equivalent, of course.

1. less abrupt "breakaway"
2. better protection against road hazards
3. lighter weight for the wheel/tire package

Like most aspects of car design, it's tradeoff. Short sidewall tires do have crisper handling and tend to build up less heat. I think that in the widths that are practical on a 4th gen, a 17" tire with a 40 aspect ratio (ie a 275 or 285/40/17) is a good compromise. If you want maximum dry grip, a 315 in the rear is worth the disadvantages of the low aspect ratio (35). But I would avoid an 18" rim due to the weight and the possible need for a tire with a very short sidewall.

Rich Krause

 

One of the "limitations" of the F-Body is the "live" rear axle. The suspension just isn't compliant with extremes of motion the wheels need to make relative to the body. The IRS on the Corvette is far better able to use the benefits of the thin side-wall, wide tread tire, as are the Euro "road racers" - BMW, Audi, etc.

What size, type, aspect ratio, compound you select depends entirely on how you plan to use the cars.... you can be John Force on 28x15" slicks, you can be a canyon carver on low profile wide tires, you can ride on 'dubs for the show circuit..... depends what you want your car to do.

 

Brakes may not have been mentioned yet. One really good reason for larger wheels is to fit larger calipers behind them. So if that's the case, the wheel choice becomes secondary to the brake choice. Pick the largest brake you think you'll be using, then find the smallest wheel that goes around it.

Of course that doesn't really apply in this example about drag racing.

Dave

 

Xscream, you make a valid point and I had to think about it. However by that logic, slicks would not make a difference either(assuming identical compounds and sidewalls). In the Bosch automotive handbook, they claim stopping distances on dry pavement actually get shorter as a tire gets worn(this is opposite on wet pavement so don't go driving around on bald tires). This leads me to believe that there are some factors being overlooked in this simple(and logical) statement that you quoted.