In 2000 and 2003 we presented you with buyers' guides
to road legal semi-slick tyres (see http://autospeed.drive.com.au/cms/A_0593/article.html and
http://autospeed.drive.com.au/cms/A_1883/article.html).
Well, there have been quite a few changes in this segment and it’s time to bring
you up to speed with what’s on the market.
But, first, why would anyone want to
buy such a barely legal set of tyres?
Semi-slick tyres employ a softer rubber
compound than normal high-performance tyres and the tread pattern has
fewer grooves to further improve dry road grip. These tyres are also resistant
to high temperature operation (such as when driving on a racetrack) and have
stiff sidewall construction to maximise chassis feel and response. But there are
a couple of factors to be aware of. The soft rubber compound gives
poor wear characteristics (you’ll typically get less than 15,000km from a set of
tyres) and the lack of tread means wet weather grip is generally poorer than conventional tyres.
In addition, you should double-check
legality and make sure that your vehicle insurer is informed of their fitment.
Most insurers will let you go ahead with semi-slick tyres so long as they have
official street-legal approval – this is identified by the letters DOT (an
abbreviation for the Department of Transport) or E (the European legal
compliance symbol). Be on the lookout for tyres marked ‘Not for Highway Use’ or
‘For Racing Use Only’.
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Comparing
Tyres
Some
tyres carry Uniform Tyre Quality Grade (UTQG) data which is a valuable tool when
comparing to other brands.
Here’s
how it works.
Let’s
use the example of a tyre having a UTQG label of 60-A-C.
The
number 60 identifies the tyre that has a tread wear index of 60 (the lower the
number, the softer the tyre). The next two letters identify the traction
index and temperature resistance index, respectively. A school type grading system is used –
an A, B or C grades are awarded.
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DOT Legal Semi-Slicks
Note that the tyres listed here are available in
Australia and/or the US – it some instances, other countries may have the same
tyre available under a different name. For comparative purposes, the prices
quoted are for a 225/50 16 size (where possible).
BF Goodrich
Since our previous Stick Like Gum feature, there
has been no change in the BF Goodrich range of street legal semi-slicks.
"Hero-making traction and control come to the
strip" is the catchphrase for the BF Goodrich G-Force T/A Drag Radial. With a
primary focus on quarter mile performance, the G-Force T/A Drag Radial is fully
street legal and features two full-width steel belts and 5.5/32 of an inch tread
depth giving maximum straight-line traction and predictability. It is also
reputedly "comfortable to drive to and from the strip."
The new Drag Radial T/A is available in selected
sizes between 14 and 18 inch.
Speed Rating: Not available.
UTQG Rating: 0(!)-B-C.
Approximate Price: A 225/50 16 size is not
available but a 255/50 16 costs around US$200.
Dunlop
In late 2003, Dunlop released a tarmac
rally tyre which carries road legal identification. The Dunlop Motorsport
Direzza 02G is designed by Dunlop race engineers and complements the existing
Formula R range.
The Direzza 02G uses a reduced tread depth, high
stability pattern and race tyre construction and tread compound. This product
has so far proven successful in various Targa rallies. It is available in sizes
from 165/60 13 to 265/35 18.
Another relatively new addition is the Dunlop SP
Supersport. The Supersport has a greater number of tread cuts making it more
suitable for street use and it is available in a selection of large diameter
sizes – 17 to 19 inch.
Old faithfuls, such as D98J (which is now
effectively superseded but remains available in limited sizes), the D01/2J,
Formula R SV98 and a wet weather version - the D93J - are also
available.
Formula Rs have won the Bathurst 12 Hour, the
Eastern Creek 12 Hour, Targa Tasmania, three Peaks Rallies, Dutton's GP Rallies,
Indy GP Rallies, the Panama Alaska Rally and more. Formula Rs are available in
sizes from 165/70 10 to 255/40 17, while the Formula R SV98 comes from 195/55 15
to 265/35 18.
Speed Rating/UTQG Rating: Not available.
Approximate Price: Around AUD$400 for a 225/50 16
depending on model and availability.
Nitto
A newcomer to the market is the DOT approved
Nitto NT555R Extreme Drag Radial tyre. This tyre is primary designed for
drag use but is quite streetable and can go more than 20,000km in normal use.
NT555Rs are manufactured with a tread depth of 6/32 of an inch and use a
specially formulated racing compound to provide maximum traction.
Nitto NT555Rs are available in diameters 14 to 18
inch and widths from 205mm to 335mm.
Speed Rating: All V rated.
UTQG Rating: 300-A-A
Approximate Price: A 225/50 16 size is not
available but a 245/50 16 costs around AUD$300.
Hoosier
Only just DOT approved is the recently
released Hoosier's Radial A3S05/R3S05. These tyres use dual grooves
around their perimeter, are quick to warm up and are resistant to high
temperature operation. They’re great for autocross, time trials and hill climbs
but, given their near tread-less appearance, we’d suggest thoroughly checking
out their legality before purchasing...
Combined, the A3S05 and R3S05 are available in
sizes from 185/60 13 to a massive 335/30 18.
Speed Rating: All Z rated.
UTQG Rating: 40-C-A
Approximate Price: US$200
Kumho
VictoRacer V700 is the premium performance
tyre from the Kumho range. This product is fully moulded, features a highly
developed tread compound and an asymmetric pattern to provide maximum cornering
power. Steering response is also outstanding thanks to the very stiff sidewalls.
A tread depth of between 5 to 6/32 of an inch indicates this is extreme
performance tyre.
The latest DOT approved competition tyre in the
Kumho range is the Ecsta V70A (aka V700).
The Ecsta V70A uses Kumho's specially formulated
high grip silica competition tread compound combined with a directional design
that features wide tread ribs in the shoulders and intermediate tread blocks to
maximise dry cornering grip. Its directional tread design also helps provide wet
traction when run at full tread depth. The Ecsta V70A is moulded with 6/32 inch
of tread depth in its two major circumferential grooves. The V70A is also
lighter than the Victoracer and, unlike the Victoracer, you can remount the
Ecsta ‘inside-out’ to extend its serviceable life.
VictoRacers are available from 205/60 13s up to
315/35 17s while the Ecstas are available from 175/60 13 to 335/30 18.
Speed Rating: The VictoRacers are V-rated in 13-14
inch sizes and Z-rated for 15-17 inchers. The 13 to 15 inch Ecstas carry an H, V
or Z rating while larger diameter versions (16 to 18 inch) are all Z rated.
UTQG Rating: 50-A-A.
Approximate Price: VictoRacer US$160. A 225/50 16
size is not available in the Ecsta but a 225/50 15 costs around US$150.
Pirelli
The P Zero C is Pirelli's most purposeful
tyre that is legal for road use - although it is mainly intended for
circuit use. It features "excellent road holding near the limit, constant
performances under very high speeds and a high resistance to the
physical/mechanical stresses arising from circuit use". With a ZR (240 km/h)
rating, the P Zero C also has an asymmetric tread design possessing extra large
outer blocks to allow maximum road holding and stability in bends.
In addition, there’s now the Pirelli P Zero
Corsa DOT legal competition tyre. Designed for driver training schools and
special event lap days, the P Zero Corsa is moulded with 6/32 inch of tread
depth in its grooves and is available unshaved for use on damp tracks. It can
alternatively be shaved to between 3/32 and 4/32 of an inch tread depth for use
on dry tracks.
P Zero Cs are available in sizes starting from
195/50 15 up to 245/45 16 while the P Zero Corsas are available from 205/50 17
to 315/30 18.
Speed Rating: We believe they are all ZR
rated.
UTQG Rating: Not available.
Approximate Price: Around US$210 for a Pirelli P
Zero C. A 225/50 16 size is not available in the P Zero Cosa DOT competition
tyre range but a 225/45 17 costs around US$225.
Yokohama
Yokohama has recently released an all-new DOT
legal semi-slick tyre – the Advan A048. This tyre is ideally suited for
targa type road events, club sprints, lap dash events, circuit racing and club
level events such as supersprints, motorkanas and hill climbs. It is also the
official control tyre in a range of Australian motorsport categories including
the V8 BRutes and the Production Car Championship. Tread depth is 6/32 of an
inch but they should be shaved for maximum grip on a dry circuit.
The older generation Yokohama A032R is also
available at most performance retails. The A032R (successor to the A008
series) is a proven top performer which offers a good combination of dry and wet
bitumen grip, progressive breakaway and clearly visible tread - which reduces
the likelihood of being pulled over by the police for ‘bald’ tyres...
The A048 is available in sizes from 205/50 15 to
315/30 18 while the A032R is available from 175/60 13 to 255/40 17.
Speed Rating: In the A048s, there’s
a range of H, V, W and Y speed ratings depending on size. In the A032R range,
the speed rating for 60 series tyres is H, 50 series are V and 40/45 series are
Z rated.
UTQG Rating:
60-A-A
Approximate Price: Around US$191 for an Advan
A048. A 225/50 16 size is not available in the A032R range but a 235/40 17 costs
US$146.
Bridgestone
The Potenza RE540S and RE55S are
Bridgestone's offerings. The older RE540S (which is gradually being phased out)
is a directional tyre with a standard tread depth of 5.2mm and an
extra-stiffened sidewall. This sidewall is rumoured to be amongst the firmest in
this category of tyre and it has a reputation for excellent balance between dry
and wet weather grip. The latest release RE55S (pictured) is very similar but is
intended more towards dry performance and comes in larger sizes.
The RE540S comes in a choice of sizes from 165/65
13 to the 205/65 15. The RE55S comes from 185/55 14 to 285/30 18.
Speed Rating: In the RE540S and RE55S range, the
60 series tyres are H rated, the 50-55 series are V rated and the 35-45 series
are Z rated.
UTQG Rating: Not available.
Approximate Price: Around AUD$300.
Falken
The Falken Azenis RT615 is this company's
most appropriate road legal tyre. Although not as soft as some of the other
tyres listed here, the RT615 is suitable for competition use and should deliver
good grip thanks to its large tread blocks. Expect tyre life slightly better
than the other tyres mentioned here.
The Azenis RT615 is available most common sizes
from 175/60 14 up to 315/30 18.
Speed Rating: H or W depending on size.
UTQG Rating: 200-A-A.
Approximate Price: US$120
Toyo
Toyo's most popular DOT approved competition
radial is the Proxes RA-1.
Designed for "touring racing" and carrying CAMS
approval, it uses steel wire reinforced sidewalls, an aggressive directional
tread pattern with a 8/32 inch (6.35mm) depth for exceptional wet weather
traction. It can also be shaved to improve dry weather lap times. Internally,
the RA-1 features two wide steel belts, jointless edge and cap construction as
well as a special tread compound to optimise adhesion and durability. In this
segment, the RA-1 is also quite long lasting.
In addition, you can now find the Toyo Trampio
R1-R which is a unique hybrid ultra high-performance/race tyre designed for
club motor sport competitors that regularly use their vehicles on public roads.
Due to its aggressive tread pattern and tread depth, the Trampio R1-R is
particularly effective for hill climbs and lap dash events on wet or dry tarmac.
The original tread depth is up to 7mm but Toyo recommend shaving it to 2 – 3.5mm
for maximum dry performance.
Another new addition is the Toyo Proxes
R888. The R888 has a low-void ratio for minimised tread squirm on dry tracks
while the new groove design optimises water drainage from the contact patch.
Round tread shoulders are also employed for progressive turn-in. This tyre
provides competitiveperformance for a wide range of motorsport
disciplines from hill climbs to endurance racing.
The Proxes RA-1 is available in a reasonable range
of sizes from 185/60 13 to 335/30 18. The Trampio R1-R is available in only 16
and 17 diameters. Proxes R888s are available from 185/60 13 to 295/30 18.
Speed Rating: The smaller RA-1s up to 225/50 14
are V rated, while the larger sizes are Z rated. The R1-Rs are V rated while the
majority of Proxes R888 are Z rated
UTQG Rating: The RA-1 is listed at 40-A-A but we
are unable to find UTQG data on the Trampio R1-R and Proxes R888.
Approximate Price: AUD$310
Contacts:
Kevin Kenny Tyres (BF Goodrich) +61 8 8232 5622
Stuckey Tyre Service (Dunlop) +61 3 9386
5331
http://www.stuckey.com.au Kym Davis
Tyres (Hoosier, Bridgestone) +61 8 8332 0800
Tyrepower (Falken,
Toyo) +61 8 8370 2195
Tire Rack online (Hoosier, BF
Goodrich, Yokohama, Kumho)
http://www.tirerack.comToyo Tyres
Australia
www.toyo.com.au Trackside Tyres
(Bridgestone, Falken, Hoosier, Toyo)
+61
3 9761 5557
http://www.tracksidetyres.com.au
VPW Australia (Nitto) +61 3 8405 9280
http://www.vpw.com.au/
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