Does anyone run a 205 tire on a 6 inch rim?

[twobone]

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

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

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:

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.

 

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

 

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.

 

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.

 

Camber Settings

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 overheating.

Increasing inflation pressures to prevent the outside tread shoulder overheating

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.

 

Tread Temperatures

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.

 

Street use

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.

[480rider]

My car came with a setup for running Hoosier bias-ply slicks. When on the slicks, I run 7" in front and 8" in back, on 13x6 wheels all around. I've also run the car on Hoosier R6 DOT track tires, 185 in the front and 205s in the rear. The guy who mounts my tires had no issues whatsoever with the 205s, and to my eye they look to be a much better fit than the 8" slicks.

 

(I do, however, notice a substantial difference in handling. My scale shows that the DOT tires add about 7 pounds per corner, and that added weight dramatically changes how the car feels on track. The car goes from feeling "squirty" to "sluggish.")