Tire profile vs tire performance

Good question. My 'guesses' would be ; too limiting on the 'swept area' of the brakes(probably a 'fatness'- if you meant 'arc length'/whatever - limit for clearing gasses and dust) and ,again - maybe, the sidewall thickness starts adding weight or other factors (more heat?) detrimental to the 'system'. Interesting.

I have read of 1 or 2 autox-ers that stay with 16s saying there's no improvement going to 17s, and likely 16s for rallyx would help in rim longevity but I guess construction factors and course topography play as big a roll.

hmmm...yeah, I'd like to know too.

Carl

According to the tirerack tech archive the sidewall is typically 100% polyester.

Well, slotted rotors work better within the same rotor diameter and going from

16" to 17" allows for a 1" increase in rotor size so if you have 10" rotor with 16" and you can now clear 11" rotor you have 11x11 / (10x10) = 21% greater area to dissipate heat. I just don't understand why can't they just make a 21% fatter rotor. WRX has 24mm rotors and STI has 30mm. Granted, STI rotor diameter is larger, but there is nothing that prevents Brembo from making say 45 mm rotors. Would that require using wheels with larger offset to clear fatter calipers?

Any pictures/drawings of wheel/tire/brake cross section of a Formula 1 car?

Formula 1 wheels are fixed in size by the regulations, to enforce reduced performance. Combined with very very stiff suspension setups, the result is that a large percentage of the suspension travel on an F1 car is in the sidewall of the tyre, which is undamped. AIUI this makes the transient behaviour of the car much more difficult to model and control. Therefore, you probably would not want to take this route with a road car.

Makes sense.

Carl

You're joking, right?

It's an extremely wide 13" rim. Apparently the width is allowed to vary. I mean - they allow rims that are wider than their height. I also read that the wheel makers often won't deliver their wheels to F1 teams until they get their final tires, maybe a few weeks before the start of the season. And steel seem to be legal. Apparently F1 teams don't subscribe to Jiri's logic that steel is good enough. Really - a magnesium alloy is probably the ideal material for its light weight and stiffness.

"12.3 Wheel material : All wheels must be made from an homogeneous metallic material.

12.4 Wheel dimensions : 12.4.1. Complete wheel width must lie between 345mm and 365mm when fitted to the front of the car and between 440mm to 460mm when fitted to the rear."

Yeah, the tyres are very wide, because they have a lot of power to put down, and they're grooved, because allowing narrower tyres would significantly reduce drag, increasing top speeds, which is Not Safe. IANA vehicle dynamicist, so I can't tell you what aspect ratio does to tyre dynamics. F1 wheels and tyres, like much of F1, are determined much more by the rulebook than by the technical ideal, which would be more like what Peugeot have fitted to the 908 LMP1 race car. They probably have some rules on wheels but LMP1 is more flexible than F1, I think.

And how does the wheel know where has it been fitted to?

What wheels sizes and tires are used on 908 and how are brakes cooled on LMP cars? it looks like the fit in the wheel wells is tight with not much airflow

I don't know what size the wheels are, sorry. The only detail on the Peugeot Sport website is that they're BBS magnesium wheels - the website doesn't have photos of the real car though, so perhaps the technical details will be updated at some point.

Brake cooling will be achieved by ducting air into the wheel well from the two channels that run between the wheelarches and the nose - if you look at the photos of the front on

you can see the brake duct intakes. The air is then vented through the alloys and out sideways.

I'd have to say because a tall sidewall is the opposite of what a performance tire is, which is all about sidewall flex.

Even in a straight line, a tall sidewall will flex more than a low profile one will (think of a brush and then cut the bristles in half and check the stiffness again.) Flex = heat. Heat is bad. Ironically, if you check the hardness on most "high performance" tires with a Z or Y speed rating, you'll find the rubber is rock hard at room temperature so they don't come apart under sustained high speeds.

I have one question -> what do YOU define a high performance tire as?

if you're defining it based on speed rating, then see my comments re:sidewall flex.

These are high performance tires and are completely different designs:

1-Ice racing tires. 2-Drag racing tires. 3-Tires designed for autocrossing. 4-Tires designed for a 500 mile endurance race.

1-soft tread compound at -30

2-soft sidewalls for maximum launch 4-designed to get sticky with minimal warmup 5-designed to handle heat from extended high speed running.

heck, even in NASCAR they use different compounds at different tracks. They even have right side and left side tires for ovals.

Ray

Good point. I'll get the tires with the lowest speed rating that the tire shop would sell. Thanks!

for max performance summer tires I'd define it as "grips tenaciously to the wet pavement at the temperatures above 45F" and speeds in 0-120 mph range. Ventus R-S2 and Ecsta MX worked well for me. Drooling over F1 GS D3 now.

I could see how that could be a problem on the track with the average speeds in triple digits, but don't see how that helps in driving on public roads.

How are ice racing tires different from "performance winter" and "studless winter" tires for the street?

Ok. My curiosity is all about the technology carryover and applicability to the street legal tires.

they sell tools to measure the rubber "softness" - but that's not always the best indicator either, because room temperature hardness doesn't always translate to operating temperature hardness, and unfortunately, you have no cheap way to "test" multiple brands of tires on your own car...

fwiw, I have the Ecsta MX's on my Trans Am. They weren't any better than the OEM Goodyear Eagle F1's. Probably worse. IOW, I won't be replacing them with another set.

And I define high performance street tire as dry grip, which is why my next set of tires for it will be BFG KD's. Not the KDW, because I try not to drive it in the rain.

well, I saw rec.autos.sport.f1 in the newsgroup line...

I was comparing them against each other - they are all a high performance tire yet other than being black and round are completely different applications.

I see. If it's any consolation, tire selection and pressure is a black art if I ever saw one.

Ray

There are a whole lot of Z/W speed rated all-season tires that aren't exactly rock hard at typical spring temperatures. There seem to be a lot of things done to reduce temperatures at high speeds, like the stiffer sidewalls, nylon caps, and extra sidewall material. I'm sure some advances might allow a softer compound to hold up when it heats up. It might be a little squishy though.

I'm pretty sure when you get to a Y speed rating, a harder compound is almost a necessity.

I can't tell much of a difference between Ventus R S2 and Ecsta MX and that's 5th vs 15th place in C&D test. Haven't tried F1 GS D3 yet. F1 GS D3 is significantly more expensive and is not available in 195 55 R15. My only choice now is to put them on outback nadasport but suspension is so soft it very silly to do that. RE-960s for me?

Do KD offer noteceably more grip than KDW in the dry? Do you know of they break away in a controllable fashion in the wet?

I was wondering in the original post if tires with very tall sidewall work in F1 with speeds over 200mph why there are only crappy compounds available for street tires with tall sidewalls and speculating that rice kids are paying for R&D on 18"s with rubber band tires, so the rest of us have to live with those tire sizes as well if we are to get any grip. Probably the consumer retorts public is buying crap like triple treds in high sidewall sizes and there is no demand for 60 or 70 profile f1 gs D3s so Goodyear does not make them in that size?

Haven't seen any tires for racing on ice on tirerack so had to ask what are they. Any model numbers you have in mind or those are one-offs provided directly to the race teams?

It sucks to be left in the dark by the tire companies, isn't it?

KD: Number one in dry cornering*. What it is: Track-ready ultra high performance tire with near race-level grip. Multi-time magazine showdown winner. The highest dry cornering mark (1.08g) one leading testing organization has ever recorded for a full tread depth street-legal tire*. Who it?s for: High-performance car owners and weekend track event competitors seeking absolute no-compromise, dry cornering performance.

*As of 6/10/04. For additional information go to

KDW: Bringing ultra high performance to more vehicles than any other tire line. What it is: Your go-to ultra high performance tire.With 92 sizes ? from 15? to 24? ? it covers more car, truck and SUV fitments than any other UHP tire line. Many unique sizes and a choice of tread patterns for ultimate customization. Excellent wet and dry traction. Who it?s for: The vast majority of owners of stock and customized performance cars and trucks seeking outstanding performance and improved appearance. Especially Plus-1, Plus-2, dub and other custom sizes.

All I care about is dry grip. You don't want to be driving a KD in the rain.

I can't find a tire size on an F1 tire, but it looks low profile to me - a 355/30-15 has a sidewall almost the same height as a 205/50-15...

and the tires in F1 are purposely crippled to reduce cornering speeds. You can read about it on formula1.com

Oh, they'll all convince you their products are all the best. ;) After going from brand to brand, I'm staying with BFG for the time being until someone can convince me to switch.

Ray

I can never remember the formula, but assuming that for highest grip, the teams fit the biggest wheels allowed, that would mean a rolling diameter of 660mm, with 355mm wide wheels at the front and 380mm wide wheels at the back. The front tyre tread width may not exceed 270mm. I'm actually struggling to find the rule that sets the size of the rims, but I thought they were 13". It must be in the regulations somewhere but for some reason it's eluding me today.

...'Why aren't anyone using square tires?'

HAAHAHHAHAAHAHHAAAHAHAHAHHHHAAAAAHAAHAHAHA ...hee [cough]