Discussion in 'Useful Links' started by Odin, Dec 6, 2007.
Sorry for the slightly OT, but I'm considering a set of 15" rotas or something for the R, for track use. As I'm hoping to get my hands on a '88 civic as well, I thought it'd be nice to be able to use them on both cars.
However, I've never tried 15" wheels for track use, I see that it's recommended, but I can't help but wonder if the tyrewalls won't just... give in? How do they feel compared to 17" for instance? And what dimensions are recommended for the 15"/16" wheels?
Very informative web site Bob thanks for sharing it...
I have it bookmarked.
Have been out on a track with standing water with the R888's yet but thing that will change come Sunday at Knockhill. Pity the treads almost spent though... :doh:
Think you will be surprise ,how good R888's are in the wet (low boost) and away you go !
The tyres are rated for load as well as speed, this does not make any difference if there 15 or 16 and 17, the 15's I will be using soon are rated to take more than most as the side wall has been strengthened. Check with the makers guide to find out the rating of each tyre.
MOTOR SPORT RADIAL TECHNICAL INFORMATION TO OPTIMISE TOYO MOTOR SPORT RADIAL TYRE PERFORMANCE
QUICK REFERENCE LINKS
Cold inflation pressures
Hot inflation pressures
Camber & inflation pressures
Tread depths / Buffing
Parallel Import Toyo Motor Sport tyres
Using different tyre patterns and types on one vehicle
Cold Inflation Pressures
Optimum cold inflation pressures are chosen to achieve optimum hot inflation pressures.
Optimum cold inflation pressures are determined by: 1. event distance and, 2. vehicle weight and 3. camber settings. Pressures shown below are for inflation with compressed air.
Event Distance - Dry Tarmac
Vehicle Weight 4 laps or more Very short - hillclimbs or maximum 3 laps.
Very Light < 800kg 17 - 22 psi 20 - 26 psi
Light 800kg - 1000kg 20 - 26 psi 21 - 28 psi
Heavy 1000 - 1400kg 23 - 27 psi 26 - 32 psi
Very Heavy > 1400kg 27 - 35 psi 31 - 38 psi
Hot Inflation Pressures
Hot inflation pressures indicate the suitability of the cold inflation pressures. Where hot pressures are too low, start with a higher cold inflation pressure or vice-versa. Pressures shown below are for inflation with compressed air.
Vehicle Weight Optimum Hot Inflation Pressures
Very Light < 800kg 22 - 29 psi
Light 800kg - 1000kg 24 - 32 psi
Heavy 1000kg - 1400kg 28 - 40 psi
Very Heavy > 1400kg 37 - 42 psi
Hot Inflation Pressures Guide:
The hot inflation pressures shown above have a large range. This takes into account the variances in vehicle weights within the ranges shown, as well as axle weights, for example: a front-engine, rear-wheel-drive vehicle with a front weight bias will usually give best results with hot pressures that are 2-4psi higher on the front axle compared to the rear axle.
Changing hot inflation pressures by small amounts ( 1-4psi ) can be used to fine-tune handling:
Reduce Oversteer reduce rear axle hot inflation pressure
Increase Oversteer increase rear axle hot inflation pressure
Reduce Understeer reduce front axle hot inflation pressure
Increase Understeer increase front axle hot inflation pressure
Changing hot inflation pressures to change handling bias should be used for fine-tuning only. Improving overall grip levels should be done by tuning spring rates, sway bars, suspension geometry etc., using lap times and pyrometer readings to asses changes.
Hot Inflation Pressures NOTE: Tyres with full tread depths used on dry tracks will have more tread flex and therefore more heat build-up compared to tyres with reduced tread depths. One result of this heat build-up is slightly increased pressure build-up. The amount of pressure build-up will decrease as tread depth decreases.
Hot & Cold Inflation Pressures for Proxes RA1 & Proxes R888: Due to a casing construction that has less sidewall deflection compared to the Proxes RA1, the Proxes R888 will provide optimum performance with hot and cold inflation pressures which are 2 - 4psi lower compared to the Proxes RA1 with the same using conditions.
USING NITROGEN COMPARED TO COMPRESSED AIR FOR TYRE INFLATION
Nitrogen behaves quite differently compared to normal compressed when used to inflate tyres. When subjected to heat, compressed air will expand at a greater rate compared to nitrogen. For this reason, all factors being equal, there will be less pressure build-up when nitrogen is used for tyre inflation compared to normal compressed air. For this reason cold inflation pressures should be higher when using nitrogen inflation compared to using compressed air.
The advantage of using nitrogen compared to compressed air is that cold inflation pressures are closer to optimum hot pressures. Steering feel and response will be superior with the higher inflation pressures for the first 2 - 3 laps compared to using the lower inflation pressures suitable when using normal compressed air. Nitrogen inflation also provides less variance in inflation pressures, therefore more consistent tyre performance and steering response. For more information regarding nitrogen inflation, please refer to the technical article "Inflating tyres with nitrogen compared to compressed air".
A good "rule of thumb" to determine the optimum cold inflation pressures for nitrogen inflation: 1. determine the usual amount of pressure build-up that occurs using compressed air, 2. halve that amount, and 3. add the amount from step 2 to the cold inflation pressure used for compressed air.
NOTE: When using nitrogen for tyre inflation, ensure tyres are purged of compressed air and moisture, otherwise the advantages of nitrogen inflation will not be realised.
WET CONDITIONS & INFLATION PRESSURES
For wet tracks (STANDING WATER) increase pressures by 4-10 psi compared to dry track pressures. Increasing the pressure for wet tracks makes the tyre's contact patch smaller, making the tyre less susceptible to aquaplaning.
There is less heat build-up on wet tracks, therefore less pressure build-up. This is another reason cold inflation pressures need to be higher than those used for dry conditions.
For optimum performance on tracks where there is standing water, tyres with new depth or close to new tread depth will provide optimum performance. Buffed or worn tyres (3 - 1.5mm tread depth) will be susceptible to aquaplaning where there is standing water.
It is recommended that tyres used on wet or damp tracks are given a short "scrubbing-in" session before they are used competitively to remove the layer of mould release on the new tyres. Without "scrubbing-in" the tyres will be slippery until this layer of mould release agent is worn away.
Toyo motor sport radials will provide optimum cornering grip with camber settings between negative 3 and 6 degrees on steer axles. Where adjustment is possible, negative camber on drive axles will also improve cornering grip. Optimum camber angles will provide optimum cornering grip, and therefore will be an important contributing factor for improving lap times.
NOTE: On some vehicles a lack of negative camber can over-heat the outside tread shoulder causing grip levels to drop-off suddenly and in some cases cause blistering of the outside tread shoulder. Large heavy, front engine cars are most susceptible to this type of tyre damage.
CAMBER SETTINGS & INFLATION PRESSURES
Where camber adjustment is limited or class rules limit the amount of negative camber allowed, increasing cold inflation pressures may help to prevent the outside tread shoulder over-heating. This also applies to vehicles that are used on the street as well as the track, where the camber settings are a compromise for this dual purpose. Where this is the case, adding 3 - 4psi to recommended cold and hot inflation pressures usually helps to prevent the outside tread shoulder over-heating. Increasing inflation pressures to prevent the outside tread shoulder over-heating where more negative camber is needed for optimum tyre performance and grip is only recommended where camber adjustment is not possible, and is not always effective (testing the pressure increase will confirm wether the increased inflation pressure improves lap times).
Tread Depths & Tyre Performance on wet & dry surfaces
All grooved motor sport tyres will have some tread flex. On dry surfaces tread flex reduces overall grip levels and therefore lap times. To optimise dry grip levels with grooved race tyres, tread flex needs to be minimised. The more groove area or "void" a tread pattern has, the greater the amount of tread flex there will be in dry conditions.
PROXES RA1 - This pattern has a tread depth of 6mm or >6mm when new and has enough groove area to be very effective as a "wet" with new tread depth or close to new tread depth. For optimum dry track performance, buffing will make a large difference in grip and endurance for the Proxes RA1 and is highly recommended. Buffing will also provide more even tread wear and a slower wear rate.
PROXES R888 - This pattern has 5mm of tread depth when new and minimal groove area on the tread shoulders for optimum dry track performance. Buffing the Proxes R888 will provide a small improvement for cornering grip on dry tracks.
PROXES RR1 - This tyre is designed for wet weather use only and will provide optimum aquaplaning resistance with new tread depths. Aquaplaning resistance reduces as tread wears. The tread compound of this tyre will over-heat very quickly where a dry line begins to appear.
Click here to view Technical Information article "Buffing or shaving tyres used for motor sport".
As for most motor sport tyres, Toyo motor sport radials can be slippery when cold. Caution needs to be exercised until the tyres have had some time to warm-up. For the Proxes RA1 tread compound and the Proxes R888 & Proxes RS1 "GG" tread compound, grip levels will be low when the tread temperature is less than 55 degrees Celsius.
Optimum operating temperatures for the Proxes RA1 tread compound and the Proxes R888 & Proxes RS1 (slick) "GG" tread compound is between 75 and 95 degrees Celsius. Over 100 degrees Celsius, grip levels drop-off rapidly.
Rim widths and tyre performance
Toyo motor sport radials will provide optimum performance where the rim size allows the sidewall to have little or no protrusion from the rim flange.
Each Toyo motor sport radial product information page includes a link to download a PDF file that quotes dimensional information, including approved rim widths. Where possible, use of minimum rim widths should be avoided. For most sizes, optimum tyre performance will be provided with rim widths that are from the mid point to the maximum in the range of approved rim widths shown.
Proxes RA1: Available in one tread compound only for all sizes. NOTE: Late production Proxes RA1s will have a UTQG Treadwear Rating of 100. Older Production Proxes RA1s will have UTQG Treadwear Ratings of either 50 or 40, depending on the tyre size. The Proxes RA1 was re-tested, and due to changes with the UTQG testing procedures, Proxes RA1s will now have a UTQG Treadwear Rating of 100. There has been no change of tread compound for the Proxes RA1.
Proxes R888: All Proxes R888 tyres held in stock are "GG" tread compound. The "GG" is a versatile tread compound, suitable for a wide range of applications.
The Proxes R888 is available with the "GGG" tread compound in a small range of sizes from Toyo motor sport dealers by indent order only. No "GGG" tyres are kept in stock due to a short shelf life of this tread compound. The "GGG" tread compound is suitable for a narrow range of applications only, and has a much faster wear rate compared to the "GG" compound.
The tread compound of each Toyo Proxes R888 tyre is marked on the sidewall.
Proxes RS1: All Proxes RS1 tyres use the same "GG" compound as used on the Proxes R888.
Proxes RR1: All Proxes RR1 tyres use the "SG" tread compound. This is a very soft compound that is suitable for use in on wet tarmac only. The shelf life of the "SG" tread compound is very short.
Please contact your Toyo motor sport dealer for Toyo Technical Department for information regarding suitability of tread compounds for specific applications.
The Toyo Proxes RA1, Proxes R888 & Trampio R8881 are legal for use on public roads but recommended for competition or use on closed circuits. Grooved, street legal race tyres are designed for users who need to drive their vehicle to and from the circuit, and / or where the class regulations specify that street legal tyres must be used.
When compared to high performance or ultra-high performance tyres, when used on public roads, Toyo motor sport radials will:
1. have comparatively poor ride comfort. Toyo motor sport radials have a steel sidewall ply to minimise sidewall deflection for optimum cornering grip.
2. be susceptible to "tram-lining" / "tracking". The casing stiffness provided by the steel sidewall ply and wide belt packages used on Toyo motor sport radials make them susceptible to tram-lining caused by road irregularities common on public roads.
3. have faster tread wear. The tread compounds used on Toyo motor sport radials provide much higher grip levels compared to high performance or ultra-high performance tyres rather than long tread life.
4. be slippery when cold. Due to the tread compounds & construction types, grip levels will be low until the tyres have had some warming-up. This will be especially noticeable in cold and / or rainy conditions.
5. be susceptible to aquaplaning when used with low tread depths (3 -1.5mm) on wet roads, especially in heavy rain conditions. Users need to exercise caution in these conditions with careful monitoring of vehicle speed to avoid aquaplaning. The Proxes RA1 pattern is the exception. The Proxes RA1 has a void ratio that makes it resistant to aquaplaning, where tread depths are >4.5mm. For more information on wet road grip and aquaplaning, click here.
Using different tyre types and patterns on one vehicle
Mixing high performance street tyres and motor sport tyres on one vehicle: Some users try to address a lack of grip on an axle by fitting motor sport tyres to the axle that has a grip deficiency, and using high performance street tyres on the other axle. This practise is not recommended as it creates a grip imbalance. The fastest lap times will be achieved by addressing the oversteer or understeer problem by suspension and chassis tuning. The exception to this is drifting, where it is common to use motor sport tyres on the front axle and high performance street tyres on the rear axle to promote progressive oversteer.
Mixing different brands and / or patterns of motor sport tyres on one vehicle: This should also be avoided where possible to avoid handling imbalance. Different casing constructions and tread compounds provide different grip levels, warm-up times and handling characteristics. Having tyres of the same tread compound & construction type on both axles will promote balanced handling.
Proxes RA1: Production Cars. Refer to Schedule E in the CAMS Manual of Motor Sport.
Historic Touring and Historic Production Sports Cars. Refer to the Approved Tyre List for Groups Na, Nb, Nc, Sa, Sb & Sc in the CAMS Manual of Motor Sport.
Proxes R888: Production Cars. Approved in 2005. Click here to download CAMS Bulletin (PDF File).
Historic Touring and Historic Production Sports Cars, Groups N and S. Approved in January, 2006. Refer to the CAMS Manual of Motor Sport for class tyre size regulations. Click here to download CAMS Bulletin (PDF File).
Parallel Import TOYO Motor Sport Tyres
Important information Bulletin for TOYO motor sport tyre dealers and users regarding parallel import Proxes R888 motor sport tyres.
Separate names with a comma.