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Proxes R888

Proxes R888 was developed to deliver maximum dry handling and quick lap times for racing and track days.

With continuous centre tread and wide shoulders, Proxes R888 offers enhanced track driving.

Proxes R888 is an original equipment option for Renault Megane R26.R

A new version with improved cornering, consistent performance characteristics and longer life becomes available in 2015. Please visit the Proxes R888R page to see the tire.

 

Enhanced R-Compound Tread

Maximizes grip for better competitive handling and performance.

Unidirectional V-Shaped Tread Design

Increased tread area and limited void improves dry traction V-shaped grooves assist with wet traction.

Continuous Center Contact

Increases braking performance and dry traction.

Semi-Slick Shoulder Area

Improves grip for better steering response.

Stiff Bead Construction And Wider Tread Width

Increases cornering force for better competitive handling.

CAUTION! The rubber compounds used in these tires have unique properties that can cause them to lose some of their flexibilty when used or handled in temperatures below -9°C. This loss in flexibility can lead to potential cracking and other damage to the tire.

The example on the right illustrates the potential damage.

To minimise the chances of this happening, consumers and installers are advised to follow the instructions below:

1. Do not move or operate a vehicle fitted with these tires in temperatures below -9°C.
2. Avoid moving these tires in temperatures below -9°C
3. Before mounting or dismounting, store these tires for at least 24 hours in a temperature controlled environment of 200C or warmer and always inspect for signs of cracking before mounting. Never use tires that have cracked.
4. Remove the wheels from the vehicle and deflate the tires to half the normal air pressure during prolonged periods of inactivity or for storage.

Proxes R888 has a stiff race construction and a race tread compound. The optimum tread temperature range is between 71C and 105C measured using a probe type pyrometer, and ideally a maximum difference across the tread of 15C. The maximum hot pressure should not exceed 40psi.

Camber angles up to 5 degrees negative (normaly between 1 – 3) are permissible but the final setting will depend on tread temperatures. It is advisable to have as much positive castor as practical as castor induces a beneficial camber change during cornering.
 
It is recommend that the tires be put through a heat cycle before hard use, this will scrub them in and remove any mold release agent.
 
Initially, tire pressures should be set based on the weight of the car. The following table is a guide to intial setup. You should always begin at the higher pressure and never set a pressure below 17psi cold. Too little pressure can lead to over deflection of the tire and subsequent failure. After running in operatinal conditions, pressures can be adjusted to achieve optimum working temperature.
 
Initial Setup Guide
VEHICLE WEIGHT
COLD PRESSURE
HOT PRESSURE
Very Light < 800kg
17 - 22 psi
22 - 29 psi
Light 800kg - 1000kg
20 - 26 psi
24 - 32 psi
Heavy 1000kg - 1400kg
23 - 27 psi
28 - 40 psi
Very Heavy > 1400kg
27 - 35 psi
37 - 40 psi
 
As a tire gets hotter the pressure increases, this is due to the moisture in the air. The cold pressure you set to achieve the desired hot pressure will depend on the conditions on the day i.e. ambient and track temperature, wet or dry. If the day/track is cold you will need to start with a higher cold pressure as the tire will not get as hot therefore the pressure increase will not be so great.
 
Hot pressures must be balanced side to side. Once the tires have cooled, normally there is a difference in pressure side to side. For example, when racing on a right hand track you, the offside pressures will usually be higher than the nearside.
 
Changing hot inflation pressures by small amounts can be used to fine tune the handling of the vehicle.
Desired performance change Potential Adjustments
Reduce Oversteer
Reduce rear pressures or increase front pressures
Increase Oversteer
Increase rear pressures or reduce front pressures
Reduce Understeer
Reduce front pressures or increase rear pressures
Increase Understeer
Increase front pressures or reduce rear pressures
 
Achieving the required tread temperatures will depend again on the conditions on the day i.e. ambient and track temperature, wet or dry.
 
Competitors sometimes say “My tires started to go off towards the end of the race”, this is usually due to the tread getting too hot.
 
The tread temperatures are constantly changing throughout a race, hotter when cornering and cooler when on the straights and cooling even more when slowing to come into the pits. Therefore the temperatures you record in the pits will be lower than the actual temperature during a race. A temperature meausurement in the pits within the range given in the initial setup table above could mean the tire temperature is too high during the race.
 
Increasing your tire pressures may cause your tread temperatures to increase, more pressure stiffens the tire’s casing which results in the tread having to do more work, resulting in the tread getting hotter. Lowering the pressure may cause temperature readings to decrease. However, you should be careful not to allow the tire inflation to fall below the pressure necessary to carry the weight of the vehicle. As noted above, too little pressure can lead to over deflection of the tire and subsequent failure.
 
Inevitably changing one setting may affect the overall balance of performance of a vehicle. The optimum set up of a race car will always be the best compromise between all of the adjustable parameters to suit the conditions on the day.
Tire Size Rim Diameter Load Speed Index
185/60 R13 13 80V
185/60 R13 13 80H
205/60 R13 13 86H
225/45 R13 13 84V
185/60 R14 14 82H
185/60 R14 14 82V
185/60 R14 * 14 82H
205/55 R14 14 85V
225/50 R14 14 89V
195/55 R15 15 85V
195/50 R15 15 82V
195/50 R15 15 82V
205/50 R15 15 86V
215/50ZR15 15 88W
225/45ZR15 15 87W
195/50ZR16 16 84W
215/50ZR16 16 90W
225/50ZR16 16 92W
225/45ZR16 16 89W
255/50ZR16 16 99W
205/40ZR17 17 84W XL
225/45ZR17 17 94W XL
245/40ZR17 17 91W
275/40ZR17 17 98W
315/35ZR17 17 102W
225/40ZR18 18 92W XL
275/40ZR18 18 99W
285/30ZR18 18 97Y XL
315/30ZR18 18 98Y
335/30ZR18 18 102Y
245/35ZR19 19 (89Y)
265/35ZR19 19 (94Y)
325/30ZR19 19 (101Y)

* Not subject to EU label regulation

** Newer specification

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