Tire profile vs tire performance

[Body Roll]

All that alloy vs steel business got me thinking (plus a guy bitching
on the ford newsgroup about the lack of 80 profile tires):
why there are no high profile high performance tires?
I think RE960 which is not exactly the top performer cuts off at 60
and I think the tallest RE950 was 70 (for 14" rims).

Do Americans perceive sidewall flex as a real problem or something?
Is that a real problem? Someone mentioned that the sidewall on tires of
Formula 1 cars is pretty high and I think you can get the same
brake disk performance by making it fatter versus larger in diameter
so the breaks argument does not fly wery well.

The reason I'm asking is because 13-15" alloys should weight way less
than 17-18"
alloys and 185/60 HR14 RE960 is 18 lbs vs 32 lbs for 285/30 ZR20
Looks like the tire weight is almost directly proportional to the width
with the sidewall responsible for the "almost" part.

For 285mm W 60 profile tire with outer diameter (OD) of 26.8" I'd need
a 13" rim:

26.8" - (286mm x 60 x 2 / 100 / 25.4)=26.8 - 13.6 =13.2"

Needless to say there are no ultra high performance all seasons. let
alone max performance in 286/60 R13 size. Heck, I think there are no
street
tires in that size period.

Is the reason the "performance" looks or low profile tires for the rice
boys???

Any links to the articles over a few paragraph in length on F1 tires?

 

[Carl 1 Lucky Texan]

All that alloy vs steel business got me thinking (plus a guy bitching
on the ford newsgroup about the lack of 80 profile tires):
why there are no high profile high performance tires?
I think RE960 which is not exactly the top performer cuts off at 60
and I think the tallest RE950 was 70 (for 14" rims).

Do Americans perceive sidewall flex as a real problem or something?
Is that a real problem? Someone mentioned that the sidewall on tires of
Formula 1 cars is pretty high and I think you can get the same
brake disk performance by making it fatter versus larger in diameter
so the breaks argument does not fly wery well.

The reason I'm asking is because 13-15" alloys should weight way less
than 17-18"
alloys and 185/60 HR14 RE960 is 18 lbs vs 32 lbs for 285/30 ZR20
Looks like the tire weight is almost directly proportional to the width
with the sidewall responsible for the "almost" part.

For 285mm W 60 profile tire with outer diameter (OD) of 26.8" I'd need
a 13" rim:

26.8" - (286mm x 60 x 2 / 100 / 25.4)=26.8 - 13.6 =13.2"

Needless to say there are no ultra high performance all seasons. let
alone max performance in 286/60 R13 size. Heck, I think there are no
street
tires in that size period.

Is the reason the "performance" looks or low profile tires for the rice
boys???

Any links to the articles over a few paragraph in length on F1 tires?

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

 

[Body Roll]

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.

According to the tirerack tech archive the sidewall is typically 100%
polyester.
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=9&currentpage=38

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.

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?

 

[Phil Newnham]

Do Americans perceive sidewall flex as a real problem or something?
Is that a real problem? Someone mentioned that the sidewall on tires of
Formula 1 cars is pretty high and I think you can get the same
brake disk performance by making it fatter versus larger in diameter
so the breaks argument does not fly wery well.

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.

 

[Carl 1 Lucky Texan]

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

 

[CompUser]

@i39g2000hsf.googlegroups.com>,
(e-mail address removed) says...

Do Americans perceive sidewall flex as a real problem or something?
Is that a real problem?

You're joking, right?

 

[y_p_w]

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.

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.

<http://fia.com/resources/documents/119845428__21_12_2005_F1_regs_2008_fnl.pdf>

"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."

 

[Phil Newnham]

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.

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.

 

[Joaquín Topiso]

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."

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

 

[Body Roll]

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

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

 

[Phil Newnham]

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

 

[Ray]

All that alloy vs steel business got me thinking (plus a guy bitching
on the ford newsgroup about the lack of 80 profile tires):
why there are no high profile high performance tires?
I think RE960 which is not exactly the top performer cuts off at 60
and I think the tallest RE950 was 70 (for 14" rims).

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

 

[Body Roll]

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.

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

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

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.

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

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.

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.

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

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

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

 

[Ray]

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

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...

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.

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.

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.

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

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

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.

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

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

Ray

 

[y_p_w]

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.

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.

 

[Body Roll]

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.

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?

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.

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?

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

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?

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.

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?

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

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

 

[Ray]

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?

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
www.bfgoodrichtires.com/g-Force.

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 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?

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

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

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

 

[Phil Newnham]

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...

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.

 

[Luigi Topolino]

@i39g2000hsf.googlegroups.com>,
(e-mail address removed) says...

You're joking, right?

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

 

[Luigi Topolino]

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.

HAAHAHHAHAAHAHHAAAHAHAHAHHHHAAAAAHAAHAHAHA ...hee [cough]