[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".

[Flyer]

All I can say is I thoroughly enjoyed your thought process...

With regard to your tire width to horsepower ratio, I will add that even tire width can be misleading when it comes to road handling. The runflats that come with the 2SS, for instance, have far less grip than non runflat tires in exactly the same size that cost half as much.

I personally think we may be seeing a Mazda RX-7 like effect where narrower tires tend to be more fun. Put another way, despite the relative lack of grip in the runflats, I enjoyed them thoroughly for the 21000 plus miles I got out of them. And, I definitely appreciated how well they continued to function even with a 1.5 inch screw punched through one of them.

That said, the tires I replaced the runflats with are significantly safer in a fresh rain and pull far harder on heavy acceleration.

[vampire]

great write up. I totally get it but I quite like being able to break traction with my right foot. to some extent of course.



my '09 C6 had perfect amount of power/tire width.


most extreme case I had was with a '16 M4. too much torque, very little tire. although it was very easy to control, it took away some of the fun. then I replaced it with a C7Z that was better on this aspect than the M4. however it wasn't easy to control ``


the Camaro on the other hand... well, you know.

[WhiteMale]

I see a lot of the Chargers/Challengers that are severely under tired, they don't even look right, it's not until you get in to the SRT cars that you start to see tires that are appropriate to the HP/TQ that is available.
Guy down the street had some deep purply looking Mustang GT and I'd admire it as it was gorgeous in the sunlight but the tires were garbage on it, I'd think I can destroy him with my 1LE and his 460hp because he can't put that to the pavement, at all, he'll just spin through those.
But these things are expensive to replace, you get in to 1500-2000 for new tires every other year and you'd better have a tire budget for that.

[22SS1LE]

well the 1LE package comes with 305's in the rear

[Twizzty]

All I can say is my Camaro came with 305's in the back stock and guess what...they brake loose in 1st and 2nd whenever I want them to! It's crazy how much tq these cars have and I love it.

I actually like the trend of smaller tires on these base higher HP cars as it gives the average person some warning of what the front and rear ends are doing. Imagine if all these cars came with insane mechanical grip...the average person would push it way to hard on the street and get into trouble quick.

Also, my 2018 Mustang GT A10 base(301a) went 11.9 @ 118 on a stock 235 rear tire, that's 460 HP on a 235 tire but on a prepped surface with good DA. I was blown away with how well the GT w/A10 managed the power even with skinny ass tires.

[LT1gen6]

Originally Posted by tlr3715

. . in the name of penny pinching most car manufacturers have under tired their cars as time has gone by. .

Simply buy the P h a t tires you lust for, making whatever mods you like to make them work to your imagined advantage.

[N Camarolina]

Narrower tires relative to engine power is likely the result competing objectives the manufacturers are trying to meet. Since the end of the 70s manufacturers have always been competing on the basis of HP (increasing it with each new model offering as technology allows), since they seem to be convinced that drives consumer decision making, even in a grocery getter or family hauler. At the same time concerns about global warming have prompted tighter emissions standards and higher gas mileage requirements for new cars (why we have 1-4 skip shift babysitter). Since wider tires result in more rolling resistance and poorer gas mileage, I wouldn't be surprised if that's the reason for the manufacturers holding back on tire width.

Tire technology has improved a lot over the decades, so we likely don't need as much width to get the same handling. Then there's the trend to lower profile side walls (for looks and maybe handling improvement), which also are a likely negative for reducing tire hook under hard accel from a standing start.

[LT1gen6]

Originally Posted by tlr3715

. . 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.

Skinnier tires for F1, too. Check it out: ". . modern approach. . . the brand new P Zero F1 tyre has a tread width of 305mm at the front and 405mm at the rear, but a slightly bigger overall diameter, which grows from 660mm to 720mm.

The most significant change is a reduction in the sidewall, which now resembles that of the low-profile Pirelli tyres that have been the preferred choice of the world’s leading performance road cars for years. ."

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

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

Info source:
https://www.racecar-engineering.com/...-1-2022-tyres/

[tlr3715]

Appreciate the discussion. It’s interesting how many people are staying they prefer the ability to break the tires free easier and feel it’s more fun. Perhaps that is the majority consensus among modern buyers and are driving the change. I remember reading articles about the new GR86 and BRZ. How Subaru dialed the suspension to have more grip while Toyota calibrated to make it easier to oversteer. Most reviewers preferred the Toyota.

I think the less road drag = better MPG pointed out might also be a factor in this trend.

In terms of the 1LE, to make a fair comparison we would have to look at the 2002 SS which had the better handling package for its time.

2002 SS - 325 HP, 275 width tires - .846/HP
SS 1LE - 455 HP, 305 width tires - .670

I don’t know if I agree with saying it’s imagined benefit. Yes on a hot day with a sticky road you can still get good hook for a launch in a modern car much like I experienced in my last Mustang, but say they did offer the car with 305+ width tires or whatever, I would simply be able to get that hook and blast off acceleration much more often in driving situations.

Back when I was young and foolish and would race in places I shouldn’t, often times whoever got good hook would end up being the car in front. So there is definitely a benefit to having a tire that grips instead of one that slips.

[arpad_m]

Along with obligatory fuel economy considerations, I think the proliferation of AWD and the prohibitive cost of ultra wide tires for modern high (700-800) hp cars that would preserve the ratios you presented for late 90, early 2000s cars is also a factor here. AWD cuts the required traction for hooking from a dig in half, then with these newer electric cars you can have a motor attached to each wheel for the ultimate in fine traction control.

My 2SS would hook with a proper tire back when it was stock, so while the ratio is clearly worse than with the 2002 SS, available traction must have been deemed sufficient by GM designers.

[Twizzty]

A great comparison is a '22 Camaro SS and '02 Viper, both have around the same HP(455 vs 450) but the Viper has 120mm more rear tire(275 vs 335)...they both go 12.2 in the 1/4 mile.

That's how far everything else between the motor and tire has also advanced in 20 years.

[tlr3715]

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

[18.2SS.1LE]

You're missing a couple of key parts to the equation - tire technology advancement in the past 20 years and actual contact patch. Tire height on new vehicles with larger rim size adds contact patch area from height as well.