Why are modern cars wearing such thick shoes?

I grew up in the tire business. Started working at my grandpa's tire shop in the early 70's when I was 13 years old. I have seen tires make multiple step changes in grip, tread life, toughness, compound longevity, wet driving ability. Stopping and corning ability we now take for granted was just unheard of 45 years ago. 20,000 miles on a tire was an amazing feat. Sliding in slow motion on wet roads was awaiting anyone who pushed the limits even slightly. And no such thing as anti-lock brakes so it was extraordinarily easy to lock up and plow into the car in front of you in wet weather unless you learned to manually pump the brakes. Today's high grip, wide tire, large rim setups make cars safer to drive at high speed.
So what do people do? Drive at the new higher limits of grip. I see people do things on city interstate highways that would have caused a 10 car pile-up 45 years ago but modern tires save them. Tires are so good that manufacturers had to stiffen up the bodies in order to handle the higher bending loads generated. I put Michelin XWX supercar tires on my 65 Mustang in the mid-70's and found out just how flexible that car was. It twisted before it slid unlike with bias plys having the opposite effect. Its all about the grip, ask any race engineer, and we have a lot of it available now-a-days.
Two things I welcomed in automobile technology is the better tires and modern computer controlled fuel injection. I don't miss bias ply tires or carburetors either.

I hate to think of these new cars 10 or 15 years down the road when they have had a few owners, not had their proper maintenance, and the last owners can't afford to put the proper rubber on the rims so they run them until the tyres all but fall off.

And it is not just about sports cars. Does you family hauler have to have rims and tyres that make the 275s on 18 inch rims that are on my Disco look small?

The question wasn't about taking a car to the track. Obviously you want big sticky wide tires on the track. I have never been on a track. I've never been able to afford it. Other than looks big sticky wide tires are worse on the road.

Wide tires tramline.

They have much worse wet weather performance.

They are heavier.

They cost more.

They ride worse.

They are much noisier.

So many negative aspects to wider tires. Give me a narrow tire with a decent aspect ratio for road driving any day of the week.

You want narrow tires and low hp as fun on the street...then this should be your holy grail....

Or perhaps this is more to your taste...

For a more modern twist, this thing will be the bees knees...look at the sexy little donuts on this bad boy. It's even got enough power to get you up a hill. Guaranteed to make you smile until your cheeks hurt.

Big pimpin rims look so gooooood:

I don't think anyone will argue that modern tires are so much better. But....

For example, does the new Civic Type-R really need 20" wheels?

I think manufacturers have jumped the shark on wheel diameters. It's a way to make the tall cars we have nowadays look lower than they are.

In reply to Klayfish:

Who said anything about low HP

Tyler H wrote:

maj75 wrote:

Driven5 wrote: In reply to maj75: I can't speak for anybody else, but for me personally, the sensation of speed is more directly related to driving pleasure than the actual speed.

The "sensation" is less pleasurable for me when I have to point-by 90 percent of the cars in my run group. That why I don't track an FR-S anymore.

Can I get an amen? If you have <300hp these days and are an intermediate driver, you get frustrated on the straights. If you're advanced, you get frustrated in the corners. I'd love to see an HPDE org do Novice/200/300/400+hp run groups. I DO love that I can go buy a Sienna with 300+hp and meaty tires. A couple decades ago I used to complain about 17" wheels being to big and the tires costing too much. It's just the shape of progress. Adjusted for inflation (no pun) and performance, tires are cheaper and better than ever.

Amen!

I run the smallest wheels I can get away with, balanced against fitting over the calipers, and being able to actually find the class of tires I want for the size. Save weight, save budget.

Yeah, me too. The FoRS came with 19" rims, but I went down to 18's for my race tires. That's the smallest that will fit over the Brembo brakes. Actually, I haven't tested that theory, but street class rules only allow a 1" drop.

"Not sure what that first part means . . ."

I was remembering the problems with grip and skittishness with my old Toyota Corolla and Karmann Ghia being so light that and having such narrow tires. Putting wider, stickier tires on each made a big difference. Maybe more rubber on the road/bigger contact patch helped.

I thought that this might be one of the reasons for the thick shoes on the smaller cars today. Of course, I'm not at all savvy about tires, I've replaced the tires on my '08 Mustang twice and bought the Zero Nero Pirellis that were original issue. Good or bad . . .

Light cars don't need as much grip for the same cornering speed as heavier cars - you don't need as much force to change direction on a smaller mass. Skittishness is more likely a function of inexpensive, high efficiency, long life tires specified by the manufacturer on those cars in your experience. That said, my Locost did need grippy tires before the chassis would wake up, otherwise I just didn't get enough weight transfer to start using the tires. But that's a REALLY light car.

Modern suspension design is usually done with a specific tire in mind - at least, for those cars where they're actually trying hard. So sticking with the OE tires for your Mustang isn't a terrible idea if you're using it as the designers intended. If you've caged it and live your life a quarter mile at a time, it's possible you're outside their original design intent and you might want something different

maj75 wrote:

Driven5 wrote: In reply to maj75: I can't speak for anybody else, but for me personally, the sensation of speed is more directly related to driving pleasure than the actual speed.

The "sensation" is less pleasurable for me when I have to point-by 90 percent of the cars in my run group. That why I don't track an FR-S anymore.

That's because mostly getting passed on track does also lower the sensation of speed, as well as the sensation of pseudo-competition. It's all about finding the right balance of characteristics for the manner in which it's being used. In that regard, I largely agree with the OP (among others) that the trend for wheels/tires (and suspension tuning for that matter) on street cars has reached a point where it's generally doing nothing to improve the enthusiast's driving experience, and is often even to the detriment of such in the name of fashion, faux performance, and/or insignificant improvements to otherwise meaningless stats.

.

WonkoTheSane wrote: My theory that I've said before on here is federal minimum bumper height laws.. It'd be really hard to get a set of 15s to look good when the bumper has to be 9" higher than it did in 95.

Yes and no. On bigger cars keeping proportions is definitely part of it. But on smaller cars, the tires aren't growing in diameter nearly as much as the wheels are.

Keith Tanner wrote: That said, my Locost did need grippy tires before the chassis would wake up, otherwise I just didn't get enough weight transfer to start using the tires. But that's a REALLY light car.

Even in heavier cars, there can be some noticeable effects from additional weight transfer. As an example, my Jeep has a bit of roll steer in the rear suspension, which tends to keep the rear slip angle down and keep it from getting too tail happy when pushed in a corner on pavement.

This also leads to an interesting effect on crowned roads if you go through an intersection fast, as once you cross the crown and the body rolls outwards a little, you have to reduce steering angle to avoid tightening your line. This also means that you have to reduce steering angle a little as you get on the throttle at the apex of a turn, as the rearward weight transfer increases roll slightly (leading to the rear end steering outwards and trying to tighten the line).

But put the same vehicle on dirt for a rallycross and suddenly it's significantly tail-happy at speed, especially off-throttle. There's not enough grip to induce body roll before you start sliding, so no roll steer pointing the rear axle outwards slightly. So you build up slip angle faster in the rear than on pavement and it ends up being kinda tail-happy. A little bit of throttle to get some weight on the rear end helps balance things out.

Ah...the assumption that I take my car to the track.

I remember reading a long time ago that the Sunraycer pulled more than 1G lateral, on what look like bicycle tires.

I think the difference is simple: weight

In reply to OHSCrifle:

And CoG. The roof of that Sunraycer appears to be about waist height of the guy in the background.

fanfoy wrote: For example, does the new Civic Type-R really need 20" wheels?

No.

In reply to Cactus:

We need to see the front to really confirm. But I do expect 18s or maybe 17s will clear those brakes.

Appleseed wrote: Ah...the assumption that I take my car to the track.

Well, the original question did mention cars like the Z28 and the GT4 - so it's a good assumption. Or at least that you're interested in what track breeding does for car.

Fashion is the biggest driver. I have no real problem with wide, low profile tires on a sporting vehicle that makes use of the performance. However, a Delta 88, say, on 40 series 20's is two things- fashionable and unpleasant to drive.

Appleseed wrote: Ah...the assumption that I take my car to the track.

You don't? Isn't that what they're for? You mean my wife is right and it's not normal to have tracked every vehicle I own including my F250? I'm so confused.

In reply to rslifkin:

When you see the front Brembos, it makes sense, but you could probably fit 14s over the rears.

In reply to Cactus:

Dunno, but it looks to me like a 18" wheel would fit.

I have massive 14" rotors with Baer 6 piston calipers on one of my cars and 18" wheels clear so they could probably put smaller diameter wheels on the type R if they wanted to.

I just want decent sidewall depth on modern cars so they don't ride like a carp.

Seriously you don't need smears of tires on a Mini Cooper when the suspension is as aggressive as it is from the factory. You could knock a few fillings loose.

APEowner wrote: You mean my wife is right

Yes.

Just yes, for your health.