[arpad_m]

Originally Posted by tlr3715

Arpad_m that is interesting. Do you recall if you were accelerating with traction control off and still had good grip on acceleration?

It's been years and I didn't take notes, sorry. Overall I tried the stock Goodyear runflats, Michelin PS4S and Toyo R888Rs, with traction control on and off, various tire pressures, and was able to launch from a dig sometimes (not always), but didn't consider it a scientific experiment, so I can't tell you with certainty which combination worked the best. Surprisingly, the OEM runflats weren't bad at all for launches in hot summer weather.

Now that the car has well over 800 hp at the crank, it's obviously spin city on normal (305 wide) street tires if I hit the gas standing still, even with traction control on, I can only hit it at 40-50-60 mph, depending on the surface.

[genxer]

Nice thread tlr3715. I agree with not liking the feel of electronic throttle.

The companies have engineered toward advertisable performance specs. They use traction management to help, and to help control the car.

A natural throttle and a new e-diff with a slipper yoke side might feel better. And then go major hp/torque that could blow traction in any gear. GM wants to sell people on the idea EV performance is insurmountable - Nope.

There was a video posted in the forum about GM's test drivers being rated 1-6 (6 highest ability). The reality is most of us aren't 5's or 6's. I also say bring back 15" rally wheels. In the zombie apocalypse, we're all monsters now... I meant we're all Miata drivers now. (except Arpad)

[cdrptrks]

Originally Posted by LT1gen6

F1 cars have about a 1,000 hp. Following OP's comparative metric:

405mm width (rear) / 1,000 HP = .405mm width / HP

Not a great comparison since even the longest lasting slick F1 tires can catastrophically fail well before 200 miles of race laps because their rubber compound is extremely sticky at the expense of tire life. Also the F1 slicks have zero void area for tread unlike street tires.

[LT1gen6]

Ok. Run some of these instead

[clyde]

This thread is amazing. Thank you.

[jeffyhopper]

Originally Posted by tlr3715

I wanted to start a discussion about tire width, because I think it's a terrible trend that no one it talking about.

Basically my feeling is that in the name of penny pinching most car manufacturers (GM included) have under tired their cars as time has gone by. Horsepower has gone up substantially while tire width remains the same or has even decreased. Instead relying on stability and traction control electronics to keep the vehicles under control by utilizing the new electronic throttles to strangle the engines. I have felt for a while that many of us are paying for engine HP when, in reality, only a fraction of the power is available to us unless we are already moving quite quickly.

Brief history of my own car experience and the ratio of drive wheel tire to HP:

1999 Firebird Formula - 300 HP, 245 width tires - .817/HP

2002 Camaro Z28 - 305 HP, 245 width tires - .803/HP

2005 350Z Roadster - 276 HP, 245 width tires - .888/HP

2006 Corvette - 400 HP, 285 width tires - .713/HP

2012 370Z Nismo - 350 HP, 285 width tires - .814/HP

With all of these cars, as long as I was moving I could stomp on the gas on any dry road with TCS off, get immediate hook and take off. It is a magical feeling. The firebird didn't even have traction control and I never felt unsafe in it.

Let's look at some other classics that I have not had the pleasure of driving just for reference:

2002 Corvette - 350 HP, 275 width tires - .787/HP
2002 Viper - 450 HP, 335 width tires - .744/HP
1996 Supra - 320 HP, 255 width tires - .797/HP

Now lets compare that to some modern cars:

2017 Mustang GT performance package - 435 HP, 275 width tires - .632/HP
2023 Camaro SS - 455 HP, 275 width tires - .604/HP
2023 Corvette Stingray - 490 HP, 305 width tires - .622/HP
2023 Challenger R/T Scat Pack Widebody - 485 HP, 305 width tires - .629/HP

Quite simply tire width is not keeping up with engine power advancement. Sure tire tech has improved and you can get more grip out of the same width of tire than you could in the early 2000's, but the ratios are not even close to what they used to be.

I chose the 2017 Mustang as one of the ones to compare, because that was my last car. My experience with it was that I was only able to get the pedal to the floor in first gear if it was a dry day in 80+ degree weather. Most of the time I was lucky to get 2/3 throttle before the tires would break free or start hopping. Could rarely get the same rush of acceleration as my 2006 corvette even though the mustang had more power. Same experience when I test drove a Challenger SRT a few years ago. I have not been able to test drive an SS as there are none around here, but would imagine the experience would be the same, its too much power on a narrow tire, and I think GM has designed the stability and traction systems to create the illusion that we are getting close to full power when we step on the gas when reality might be quite different.

When I drove the older cars gas pedals were directly connected to the engines. I was in control of how much gas that engine got at all times. In fact the traction control on the Camaro operated by physically forcing your gas pedal up as it was the only way to prevent throttle. With the current electronic throttles, I never know what is actually getting to the engine. I think that realization today gave me pause.

Don't know if there is a point to this rant, but as I look to buy a new Camaro (after looking at all current options I think it's still the best for my needs) I realized that those days are over and we have lost a really great experience and connection to the engines we love plus the ability to get the power to the ground in really fun ways that I think has just faded away over time without too much notice. It's a shame, and felt I had to share this thought with some people who may also "get it".

Hello, your observation of a decreasing ratio between tire width and engine maximum horsepower from late 1990s to nowadays are valid. But it is not sufficient to justify your point.
A better way to describe whether car manufacturers have mistakenly undersized the tire on the ever more powerful sports cars would be the ratio: (maximum horsepower/maximum friction force can give by tires). With just the ratio you proposed (tire width/horsepower), it is insufficient to evaluate whether the tire width is capable for a given horsepower, because apparently modern tires are more grippy (i.e. provide higher friction force with the same area under the same downward pressure) thanks to the advancement in chemistry. Not to mention the stability control and other performance technologies have improved a lot on modern sports cars.
For your reference, gen6 Camaro ZL1 1LE (lap time: 2:45.0), Camaro SS 1LE (2:54.8) are faster on the same track with ever more impressive lap time comparing to those sports cars in the 1990s and early 2000s.To clarify, the lap times are nicely complied by Car and Driver: https://www.caranddriver.com/feature...storical-data/. Yet, you will find Camaro ZL1 1LE and Camaro SS1LE did poorly for the ratio of tire width/horsepower, ZL1 1LE is about 0.5 (325mm/650hp) and Camaro SS 1LE is 0.68 (305mm/450hp). Would you say Chevy “underwheeled” these 2 cars because they are so low on the width/horsepower ratio? If ZL1 1LE is more slippery than SS 1LE due to a lower ratio of tire width/horsepower, how did ZL1 1LE finish the track quicker than SS1LE?
Another piece of data would be, the lap time for the gen5 Camaro SS 1LE (2:54.8) is almost as good as 2009 Chevrolet Corvette ZR1(2:51.8). I can say 2009 Chevrolet Corvette ZR1(over 600hp) has a wider tire (335mm) and way more horsepower than Camaro SS1LE but failed to do proportionally better.
With these data above, maybe I can say a lower width/horsepower ratio marks the advancement in modern day sports car technology. There will always be a trade off between weight, rolling friction, maximum grip and faster lap time.

[raptor5244]

The reality is that while tire tech has improved a lot we have reached and exceeded the limit of what a front engine RWD performance tire can handle. I had those giant 335/25/20s on my C7 grand Sport and I could still light them up like crazy. This is one of the main reasons GM had to move to a mid engine architecture for the C8 Corvette. In order to improve performance they needed more weight over the rear wheels.

I agree with you regarding the all the computer controlled nannies that get in the way and tend to ruin the experience. That said, look at all the tech used to try and overcome the fact that the tires are the limiting factor. Launch control, traction control, etc.

Now you may not want to hear this but when it comes to acceleration EVs are on a whole other level and make it all seem too easy. At first you might think, well they have AWD dual motor front and rear so they get power and traction to all 4 wheels. This is true but more importantly the traction control system on an EV is very different than ICE based TC systems. In an EV you have direct control over the drive unit connected to the wheels so when the system senses tire slip it can back off and then back on and back off much much quicker than ICE based system.

Compare this to an ICE based traction control when you sense tire slip, the ECU then sends a signal to reduce timing, pull power, close throttle body, then when slip stops it signals to add power, add spark, timing, throttle body, wait for air to flow, and back and forth. There is a combination of computer and mechanical systems working together which is much slower to react. It is basically comparing a digital system to an analog system and as a result the EV traction control system is able to extract much more grip out of a tire.

I experience this all the time when I drive my Tesla Model 3 vs. my CT4V-BW and the ZL1.

I don't want to take this thread down an EV rat hole but thought it was important to put the technology into perspective as it relates to this tire grip discussion and how we will see things improve moving forward.

[LT1gen6]

No need to dilute the spirit and longing in this thread with logic and fact. The heart wants what it wants. What does it want? Fatter tires. When does it want them? Now!

[tlr3715]

I agree around the track the traction control technology benefit modern cars tremendously compared to the cars that existed prior to that technology. Modern traction control and stability systems can maximize power and grip to each wheel in ways never before possible. Also, once the vehicle is moving more horsepower will make it to the ground due to the higher horsepower ceiling compared to the older cars. Plus a 400 HP vehicle with traction trouble will usually beat a 300HP car with good hook in a drag situation or track time. More power generally equals faster. I also feel overall handling has improved quite a bit over the years. The Mustang GT I drove was a PIA to get off the line, but handled and could go around a corner a lot better than the older Camaro and Firebird I owned. That’s also not even considering the magnetic suspensions available now. Hands down modern cars win in this category.

The point I have been trying discuss is that in most of 1st gear, power is being left on the table, and the experience of putting a foot down and just taking off type of fun is now reserved to very specific road and temperature conditions instead of pretty much any dry day.

I would also be curious to know if someone were to experiment with putting wider tires on modern ZL1 cars and others that are breaking lap time records if their times would improve further with improved ability to power out of low speed corners more effectively. Or if there is a sweet spot of tire width that should not be crossed in a track setting to optimize grip and roll resistance. Is the consensus that GM and other manufactures of race competitive cars have picked the best tire combinations to maximize track performance or are they finding the most cost effective tire to hit their track target and stopping there, again leaving power on the table at lower speeds?

[ZPirate]

Originally Posted by raptor5244

The reality is that while tire tech has improved a lot we have reached and exceeded the limit of what a front engine RWD performance tire can handle. I had those giant 335/25/20s on my C7 grand Sport and I could still light them up like crazy. This is one of the main reasons GM had to move to a mid engine architecture for the C8 Corvette. In order to improve performance they needed more weight over the rear wheels.

I agree with you regarding the all the computer controlled nannies that get in the way and tend to ruin the experience. That said, look at all the tech used to try and overcome the fact that the tires are the limiting factor. Launch control, traction control, etc.

Now you may not want to hear this but when it comes to acceleration EVs are on a whole other level and make it all seem too easy. At first you might think, well they have AWD dual motor front and rear so they get power and traction to all 4 wheels. This is true but more importantly the traction control system on an EV is very different than ICE based TC systems. In an EV you have direct control over the drive unit connected to the wheels so when the system senses tire slip it can back off and then back on and back off much much quicker than ICE based system.

Compare this to an ICE based traction control when you sense tire slip, the ECU then sends a signal to reduce timing, pull power, close throttle body, then when slip stops it signals to add power, add spark, timing, throttle body, wait for air to flow, and back and forth. There is a combination of computer and mechanical systems working together which is much slower to react. It is basically comparing a digital system to an analog system and as a result the EV traction control system is able to extract much more grip out of a tire.

I experience this all the time when I drive my Tesla Model 3 vs. my CT4V-BW and the ZL1.

I don't want to take this thread down an EV rat hole but thought it was important to put the technology into perspective as it relates to this tire grip discussion and how we will see things improve moving forward.

Good points. There is an inherent limit to rear wheel drive car's traction despite the improvements in tire technology, vehicle electronics and suspensions over the years. Any time you have 50% or more a a vehicle's weight in the front of a rear wheel drive car you are going to have less traction than a mid engine or rear engine car. Of course there are things you can do to increase the traction, but there are tradeoffs in doing so.

One of the main reasons GM wanted to build a mid engine Corvette was not for the base model, but for the higher horsepower models. With the exception of all wheel drive vehicles, some of the fastest accelerating cars available are either mid engine or rear engine. The difference being the rear weight bias. Look at the high performance 911s for example.

Manufacturers also have to consider costs associated with larger wider wheels and tires, NVH issues and how a car drives when deciding how much tire a street car needs. Its a balancing act for sure. Even in my 1LE I have experienced some tramlining with the wider tires on certain roads. Most mid engine and rear engine cars have significantly smaller front tires than rear tires. That really isn't an option on a rear drive street car with so much weight on the front end, without compromising performance.

[raptor5244]

Originally Posted by tlr3715

The point I have been trying discuss is that in most of 1st gear, power is being left on the table, and the experience of putting a foot down and just taking off type of fun is now reserved to very specific road and temperature conditions instead of pretty much any dry day.

I would also be curious to know if someone were to experiment with putting wider tires on modern ZL1 cars and others that are breaking lap time records if their times would improve further with improved ability to power out of low speed corners more effectively. Or if there is a sweet spot of tire width that should not be crossed in a track setting to optimize grip and roll resistance. Is the consensus that GM and other manufactures of race competitive cars have picked the best tire combinations to maximize track performance or are they finding the most cost effective tire to hit their track target and stopping there, again leaving power on the table at lower speeds?

Totally agree, this has been the challenge for some time now. I always knew my ZL1 was faster than my Tesla Model 3 Performance in all ways except off the line. It has more power but you have to feather the throttle with the A10. In the M6 you have to deal with slipping the clutch and potential bog. Torque management and lack of tire grip a the limiting factors.

If you switch to drag radials on ideal surfaces you will hook much better in first gear but as you are mentioned it is a balancing act. Manufacturers must select a tire that strike a balance between good street manners, tread wear, cost, etc. note the ZL1 and SS 1LEs comes with F1 Supercar tires. Not a great street tire but a decent track tire and hooks pretty good when warm. The standard SS comes with less aggressive tires for better street manners and increase tread life. The ZL1 1LE has Supercar 3Rs that are basically slicks with 100 tread wear.

I am driving a CT4V-BW now and it comes with Michelin PS4S tires, which are know for being pretty street friendly but offer decent performance as well. The Cadillac team took it a bit further and released a TPC spec of the PS4S tires for use on their cars. They spec in some changes to the compound on the shoulders of the tires to improve performance on track.

[Xaxas]

This thread reeks of ignorance and just comparing numbers, "bigger = better", are you ignoring the fact that tire compound has gotten INSANELY good over the years? Plus traction/stability control aren't a bad thing, they're there to keep you alive and also prevents you from potentially killing others, you just say "hurr durr I put the pedal to the floor and car broke lose", no shit? Ever consider which type of tires the car has, the quality of the road you're in and if they're warmed up? My 1LE breaks lose at like 30% throttle on cold tires with 305 width.

And your complaint about electronics further reeks of ignorance, the reason cars are as fast and SAFE as they are today is because computers are way smarter than people, electronic throttles talk with the computers handling suspension, traction, etc to provide the best acceleration possible and for you to do what you want, when I'm on PTM and floor it during a corner, I'm not asking the car for 100% throttle input to go "faster", I'm asking for the car to go as fast as possible through the corner and the car does this by handling traction and torque.

It is a completely different experience sure, worse? Not at all, I also appreciate the feeling of a mechanical machine and that's why I doubt I'd get an electric car, and I also understand that there's even more analog cars than what I have, but I understand that the computers are there to help me have the best experience possible in my car while also being safer, instead of somehow feeling the computers have replaced some imaginary skill you thought you or the car had, understand that they are there to improve what you and the car can do.

[Flyer]

Originally Posted by Xaxas

This thread reeks of ignorance and just comparing numbers, "bigger = better", are you ignoring the fact that tire compound has gotten INSANELY good over the years? Plus traction/stability control aren't a bad thing, they're there to keep you alive and also prevents you from potentially killing others, you just say "hurr durr I put the pedal to the floor and car broke lose", no shit? Ever consider which type of tires the car has, the quality of the road you're in and if they're warmed up? My 1LE breaks lose at like 30% throttle on cold tires with 305 width.

And your complaint about electronics further reeks of ignorance, the reason cars are as fast and SAFE as they are today is because computers are way smarter than people, electronic throttles talk with the computers handling suspension, traction, etc to provide the best acceleration possible and for you to do what you want, when I'm on PTM and floor it during a corner, I'm not asking the car for 100% throttle input to go "faster", I'm asking for the car to go as fast as possible through the corner and the car does this by handling traction and torque.

Nobody is arguing here. This is more of a train of thought discussion. And, many of us are enjoying it. No need to argue or belittle those who do so.

[tlr3715]

I thought we were having a pretty intelligent and insightful conversation. I have appreciated the different perspectives and thoughts. I don’t think we need to devolve this into cursing and calling each other stupid.

I get tire technology has improved. I acknowledged that in my first post. However, if it is true that tire tech has improved enough to keep a more narrow tire/HP ratio like we see now then why did myself and others who have posted here with recent cars confirm they have trouble with first gear acceleration grip. It may be stickier rubber but there is till not enough of it to get good 1st gear grip.

Now I don’t think we have to go crazy and put tires like steam rollers on these cars, but I do think the 305s should be standard with 345 for track packages. I think that would be an overall better experience. But just my opinion.

Maybe I’m a simple guy reminiscing of times when I was young and stupid and would roll race with my friends on cool 60 degree nights until 2:00 am. We would blast off like going into warp drive and it was a whole lot of fun. No spinning, or hopping, or feathering throttles, or having power reduced electronically. Simple fun that perhaps can’t be experienced anymore.

But it’s true there is other types of fun to have. Like at a track or oversteering around a corner and I can appreciate that as well.

In terms of track performance. Show me the car that went up a tire size and got slower lap times. Or one that went down a size and got better lap times. (With same tire type of course)