Improving tires: the weak link in world's fastest cars.

[g-force_addict]

PAX tires in the Bugatti Veyron would only last 15 minutes at 250 mph.
If I'm not mistaken The SuperSport outruns approved tires speed rating.

Former racer Pierre-Henri Raphanel, Bugatti's official test driver and quite possibly the world's bravest man, says the only thing preventing the Veyron from going beyond 270 mph is tires. Raphanel, who set a production car record top speed of 268 mph in a Veyron Super Sport at VW's Ehra-Lessien test track in July, 2010, says Michelin runs the Veyron's massive meats on its tire test dyno at 270 mph -- the fastest it can spin -- for 20 seconds, then at 250 mph for 20 seconds. It repeats that cycle two more times. Then the tires explode. 2013 Bugatti Veyron Grand Sport Vitesse Front End On Track VW engineers made Raphanel run both directions along the 5.6-mile straight on the eastern side of the Ehra-Lessien track to get the record, because they knew the Super Sport's tires could not handle the g-loading on the gently curved western section at V-max. Michelin will only allow two sets of tires -- they cost about $42,000 a set -- be fitted to the Veyron before the rims -- $69,000 a set -- also have to be replaced to ensure the integrity of the bead seal at high speed.
http://www.motortrend.com/roadtests/exo ... rst_drive/

Even rims need to be replaced every other to fourth tire change.

How to go faster?

Top land speed record cars use solid aluminum rims with no rubber tires at all.
Obviously that would only work on salt flats.

Good Year Eagle land speed tires are rated at 300 mph (480 km/h) but they are narrow, made of hard rubber, inflated from 50 to 70 psi so likely they would have low grip for braking and cornering.
Maybe they can build one with threads so they can be used when raining.
http://www.landracing.com/forum/index.php?topic=9356.0
Check the specs attached table.
http://www.nwr4racing.com/goodyear-drag ... landspeed/

Mickey Thompson once built land speed tires rated at 375, 475 and 590+ mph.
http://www.landracing.com/index.php?opt ... view&id=53
I'm not sure if they continued to build them and if the tires really stood up to their speed ratings.
http://www.yellowbullet.com/forum/showt ... p?t=160259

Both Goodyear and Mickey Thompson were all bias ply so future supercars will need to have the suspension tuned away from radial tires.
AFAIK bias ply tires always have higher rolling resistance than radials.
But maybe radials can't match the strength of radial ones?

So it looks like future fastest supercars will use bias ply tires.
BTW most 'radial' race tires aren't actually radial at all. Although their plies are placed at lower angles than those on tires called bias ply.

Future supertires may be made from carbon nanotube reinforced rubber.
http://www.azonano.com/article.aspx?ArticleID=1351

Future supercars may actually have solid rubber tires. This is my best long term bet.
They would need to have strength cords embedded directly attached to the wheel to prevent the rubber strip from separating from the wheel.
They may also use carbon nanotubes for added strength.
Active suspensions will likely be needed to counteract body roll caused by the soft spring rates required to dampen the solid rubber tires harsh ride.
Such solid rubber tires would need to be inspected, rounded and balanced much more often.

What's your take on future high speed tires?

[J.A.W.]

Very different purposes, ultra-high speed runs vs regular street use..
..so it naturally will necessitate a legal/practicable delineation..
..not so very different from street/track-day/racing set-ups as have applied.. ..for.. ..like.. ..centuries.. now..

[bill shoe]

Indycar tires at the end of the CART era could do roughly 250 mph laps around Fontana superspeedway. They were pretty stone reliable. Indycars are around 2000 lbs with driver and fuel, compared to 5000 lbs for the Veyron. The Indycar had some downforce too, but not a large multiple of its weight. So maybe step 1 would be to create a different car that weighed much less than the Veyron.

Good active suspension, perhaps combined with some passive suspension bushings to provide higher-freq ride isolation, could probably allow solid wheels without pneumatic rubber. This is basically the approach of modern high-end land-speed-record cars. But these cars do not need much side force from their tires.

The whole magic of pneumatic tires is that the contact patch can twist relative to the wheel and generate good side force. All the solutions for making pnuematic tires that can cope with extremely high speed seem to pretty directly reduce this.

The shithead in me says that this problem simply reduces to: how do you improve the tires of a Bugatti Veyron so it can be driven faster than 270 mph for a couple seconds on the east straight of the Ehra-Lessien track. This appears to be the only practical application of this improvement. But I admit it's an interesting technical problem.

Also, a tip of the hat to the tire companies. 20 good tire engineers with a $20 million budget could easily create a car that was equivalent to the Veyron. 20 good vehicle engineers with a $20 million budget could not create tires that were equivalent to the Veyron tire. Expertise to make fast cars is readily available in 2014, but tires are just more... difficult.

[Jersey Tom]

Pretty simple... if you want more on the high speed durability you give up something else (cornering/braking performance... tread thickness... ride quality). It's all trade-offs.

[g-force_addict]

But I admit it's an interesting technical problem.

Also, a tip of the hat to the tire companies. 20 good tire engineers with a $20 million budget could easily create a car that was equivalent to the Veyron. 20 good vehicle engineers with a $20 million budget could not create tires that were equivalent to the Veyron tire. Expertise to make fast cars is readily available in 2014, but tires are just more... difficult.

Agree. They really need to think out of the box.


Does anyone know if the Bugatti Veyron tires are truly radial? I mean if the reinforcing cords are at 90 degrees to the tire direction?
Does Bugatti replace the tires for the opposite direction timed run? Do rules require you to use the same tires in both runs to qualify for a speed record? I would say no as salt flat racers actually recommend to replace the tires.
Has anyone (like a Veyron owner) driven it beyond 400 km/h by himself? I mean out of Ehra Lessien and not under Bugatti/VW supervision?


In 1965 aiming for 750 mph they used '25 inch wheels... extremely low angle in the fabric restrictor belts. (Ordinary radial ply tires have a belt under the tread, in which the cords run as little as 20 degrees from the direction of the tire. In land speed record tires that angle is so low the cords are almost continuous)'
http://books.google.com.gt/books?id=BOM ... ion&f=true
Page 228


In 1960 'Mickey Thompson used specially designed tube-less Goodyear slicks 30 inches in diameter, that were tested under load in excess of 500 miles per hour on Goodyear's multistage dynamometer. The tires have a carcass of low angle Nylon cord and an outer coating of pure rubber only 0.20" of an inch thick. They are mounted on 21-inch Magnesium wheels, are inflated to 100 pounds per square inch. Normally a "land speed record attempt" tire is changed at the end of each run; Thompson's proved to be so good that in trials he used the same set for more than 100 miles'
http://books.google.com.gt/books?id=0ts ... ion&f=true
Page 104


So it looks like such future supertires would likely be
-Tall. Around 30 inches tall as to reduce tire rpm for the same vehicle speed AND they also reduce overall centrifugal force at the tread. Tall tires are preferred in salt flats as tires sink somewhat. At some point in human history even the Ehra Lassien test track or Edwards base runway won't be enough for world's fastest road cars top speeds so only salt flats are left.
-Relatively low profile. Wheels more than 20 inch to reduce sidewall height and weight as rubber is the weak link while Aluminum wheels not so much. Although such wheels may have smaller open spaces compared to modern sports cars. Unless they are made of Titanium or something. BTW Titanium pothole-resistant wheels would be great even if expensive. Smaller wheel openings are more aerodynamic as well.
-It remains to be seen how narrow or wide they are going to be. Wide tires are required for low speed grip that supercar owners demand.
-A tradeoff is needed for inflating pressures. High inflating pressures reduce contact patch and deformation which reduces high speed tire temperatures and wear but the reduced contact patch hinders low speed grip. Maybe they can use a onboard fast inflation system that gets activated beyond certain speeds.

[g-force_addict]

Good active suspension, perhaps combined with some passive suspension bushings to provide higher-freq ride isolation, could probably allow solid wheels without pneumatic rubber. This is basically the approach of modern high-end land-speed-record cars. But these cars do not need much side force from their tires.

The whole magic of pneumatic tires is that the contact patch can twist relative to the wheel and generate good side force. All the solutions for making pnuematic tires that can cope with extremely high speed seem to pretty directly reduce this.

So true.
So if they decide to use solid rubber they would need to use very soft rubber inner layers to mimic air springing in pneumatic tires, and harder rubber tread compounds to limit abrasion at high speeds.


IMO they shouldn't use conventional belted tires at all no matter if they are radial or bias ply.
Just Googleing belted tires you get plenty of attorneys offering litigation for tread separation. And this on road tires at low speeds.
So unless the belts aren't strongly secured to the tire bead by overlapping cords or something they are a no go.

High speed tires usually use cap plies that are supposed to prevent belt separation.

AFAIK cap plies don't run all the way to the tire bead

So only the adhesive power prevents the belts from separating at speed.

Steel binds poorly to rubber so steel belts are reportedly more prone to separating at high speeds than those made of Nylon, Kevlar or some other textile materials.

So reinforcing cords running all the way to both beads are the key.
To prevent tread separation I think a lot of cords may be easily embedded in the tread pretty much like snow chains

Great care must be taken so that the embedded cords won't act as breaking points concentrating stresses thus actually initiating tread shredding.

[Jersey Tom]

Solid rubber would probably be a bad call... more rubber = more heat = bad things.

[J.A.W.]

True, more likely would be an automated refrigerant gas transfer cooling system for the pump-up type..

[Juzh]

Those russians from dragtimes.com are running their 2k hp lambos and gtrs time after time from 0-420+kmh on regular toyo R888 semi slicks. That includes lots and lots of burnouts before the runs. I'm honestly not quite sure what the problem is for veyron and michelin. It's not like gtr is that much lighter.

[Cold Fussion]

The difference is that Bugatti are applying proper engineering principals, while those Russians are running on hope and prayer.

[Juzh]

The difference is that Bugatti are applying proper engineering principals, while those Russians are running on hope and prayer.

And yet after hundreds of runs no accidents to report. Guess those prayers are helping.

[Tim.Wright]

Its not difficult to make a tyre do whatever speed you want. But to make one that will also performing acceptably in cornering, ride, road noise, braking, wet handling, curb strike, comfort, wear, durability as well as going through a multitude of international homologation processes is another thing.

You don't have to look far in the interwebs to see the general opinion is that Toyo's are lacking in most areas except dry grip.

[langwadt]

The difference is that Bugatti are applying proper engineering principals, while those Russians are running on hope and prayer.

And yet after hundreds of runs no accidents to report. Guess those prayers are helping.

not having to do corners or run for several minutes at a time, probably has more to do with it

[g-force_addict]

Solid rubber would probably be a bad call... more rubber = more heat = bad things.

Solid rubber has some tension resisting properties. They give some strength in resisting centrifugal force.

Compressed air has no strength in tension. Actually compressed air promotes expansion. So the only thing holding the pneumatic tires from centrifugal force are the sidewalls.

The difference is that Bugatti are applying proper engineering principals, while those Russians are running on hope and prayer.

And yet after hundreds of runs no accidents to report. Guess those prayers are helping.

not having to do corners or run for several minutes at a time, probably has more to do with it

Top fuel dragster tires already can handle 320 mph+ (500 km/h) with soft rubber.
But only for a few seconds.

[Jersey Tom]

Compressed air has no strength in tension.

Air inside tires supports / caries absolutely zero load, period. But that's beside the point.