Post by Admin on Nov 6, 2004 15:22:00 GMT
John Waller’s Technical Tips
Tube tyre types
The design of the road wheels for older Peugeot cars is such that inner tubes must be fitted, irrespective of whether the actual tyre states ‘tubeless’ on it. A modern tyre place was careless in fitting one of the tubes into the tyre and managed to crimp the rubber. The 403 had a frontal blow-out at 50mph. Later investigation revealed the inner tube had a linear crimp of about 4 inches. So when fitting inner tubes, more care needs to be taken, perhaps inflating the tube slightly in order to seat it correctly within the tyre.
Tyre pressures on older Peugeot cars are much lower than cars of today. A 403 fitted with Michelin X is to be kept at 18psi front and 23psi rear, while my 403 fitted with Michelin XZX is 19psi front and 22psi rear. My old 504 Saloon (which came delivered new with tube type Michelin XAS) was kept at 21psi front and 24psi rear. But for the exact pressure of your particular model, best refer to the car’s handbook.
Q) What is tyre slip angle?
A) It is the difference between the angle the front wheels are turned and the actual angle the car deviates. Say for example the front wheels are turned 10 degrees, the car may only change direction 8 degrees. Therefore the tyres have a slip angle of 2 degrees.
Q) So what has this to do with my car ?
A) If all four tyres are of exactly the same designation, then nothing. But if two different brands of tyre are used, care must be taken to ensure each pair go to each axle and the pair with the lowest slip angle go to the rear axle. This applies whether the car is rear wheel drive or front wheel drive.
Q) What if this rule is not adhered to ?
A) Odd handling behaviour with a tendancy to wander through loss of self-centering action. The safest handling is to ensure all four tyres are the same.
Tube tyre types
The design of the road wheels for older Peugeot cars is such that inner tubes must be fitted, irrespective of whether the actual tyre states ‘tubeless’ on it. A modern tyre place was careless in fitting one of the tubes into the tyre and managed to crimp the rubber. The 403 had a frontal blow-out at 50mph. Later investigation revealed the inner tube had a linear crimp of about 4 inches. So when fitting inner tubes, more care needs to be taken, perhaps inflating the tube slightly in order to seat it correctly within the tyre.
Tyre pressures on older Peugeot cars are much lower than cars of today. A 403 fitted with Michelin X is to be kept at 18psi front and 23psi rear, while my 403 fitted with Michelin XZX is 19psi front and 22psi rear. My old 504 Saloon (which came delivered new with tube type Michelin XAS) was kept at 21psi front and 24psi rear. But for the exact pressure of your particular model, best refer to the car’s handbook.
Q) What is tyre slip angle?
A) It is the difference between the angle the front wheels are turned and the actual angle the car deviates. Say for example the front wheels are turned 10 degrees, the car may only change direction 8 degrees. Therefore the tyres have a slip angle of 2 degrees.
Q) So what has this to do with my car ?
A) If all four tyres are of exactly the same designation, then nothing. But if two different brands of tyre are used, care must be taken to ensure each pair go to each axle and the pair with the lowest slip angle go to the rear axle. This applies whether the car is rear wheel drive or front wheel drive.
Q) What if this rule is not adhered to ?
A) Odd handling behaviour with a tendancy to wander through loss of self-centering action. The safest handling is to ensure all four tyres are the same.
