TYRE FITTING
HERE’S WHAT TO LOOK OUT FOR
Fitting tyres describes two processes: on the one hand, fitting a tyre on a rim, and, on the other hand, slipping or fitting a fitted unit on a car. While fitting a wheel on a car is a rather simple process, fitting a tyre on a rim requires some knowledge and special tools. Here’s a guide to both processes
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FITTING RIMS
When fitting tyres the rubber is mounted on the rim. This is accomplished only by using a fitting machine. To this end, the rim must be mounted on the fitting machine. The rim may be clamped, which is especially recommendable for alloy rims, or stilted, which is sufficient for steel rims. Next, the rubber flanks are greased with fitting lube. The lower the cross-section of the tyre, the more lube you should use. Then the tyre is place on the rim – keep in mind running direction – and using a fitting arm, the tyre flanks are pressed unto the inner surface of the rim. What may sound simple is the most difficult fitting step. Check out YouTube for detailed tutorials. Once the tyre is on the rim you can pump up the tyre. Note: runflat and UHP tyres must be fitted only by special body shops.
FITTING TYRES
BALANCING TYRES
Whenever you have fitted new tyres on your rims you should balance them afterwards. This applies also if you have lost a balancing weight or if you notice a wobble in steering during a ride. An imbalance occurs if the mass of a rotating body is not distributed symmetrically to the rotation axis. The faster a body rotates, the stronger you will feel an imbalance. In car tyres this can result in one-sided tread wear, steering and comfort impairments, and even damages on the car. In order to balance your tyres, you need a balancing machine which is available in every properly equipped (rental) body shop. Slip the tyre on the machine, put in the rim and tyre specs, and start the machine. After a short run – during which the wheel is rotated and weight differences measured – the weight differences of the tyre and the locations for the balancing weights to be mounted will be displayed. Secure the weights using hammer and pliers, and test again if the tyre is now balanced. Once you have balanced all tyres you can fit them on your car.
It doesn’t matter whether you have carried out the above steps on your own or have it done by a body shop – now you have fitted units that are ready to be mounted. For fitting the tyres on the car, you should take the following approach:
1) Before fitting the tyres, the car must be secured against rolling away. To this end, engage a gear, pull the hand brake, or place some wedges under the wheels.
2) Next, loosen the wheel bolts crisscross.
3) Lift the car using the jack, with the wheel just losing contact with the ground.
4) Now, unscrew the bolts completely and take the wheel from the axle.
5) Take the new wheel and fit it on the axle. Keep in mind the running direction.
6) Fasten the bolts crisscross using a spanner to a point where the wheel no longer wobbles.
7) Lower the jack until the tyre touches the ground.
8) Fasten the bolts using a torque spanner. To this end, adjust the tensile force according to the specifications in the manual. Depending on car and rim, values between 80 and 160 Nm are realistic.
9) Check tyre air pressure. Find the reference value either on the inside of the petrol cap, or in the car manual. Don’t forget the spare wheel!
10) Re-fasten the bolts after 5-20 km.
2) Next, loosen the wheel bolts crisscross.
3) Lift the car using the jack, with the wheel just losing contact with the ground.
4) Now, unscrew the bolts completely and take the wheel from the axle.
5) Take the new wheel and fit it on the axle. Keep in mind the running direction.
6) Fasten the bolts crisscross using a spanner to a point where the wheel no longer wobbles.
7) Lower the jack until the tyre touches the ground.
8) Fasten the bolts using a torque spanner. To this end, adjust the tensile force according to the specifications in the manual. Depending on car and rim, values between 80 and 160 Nm are realistic.
9) Check tyre air pressure. Find the reference value either on the inside of the petrol cap, or in the car manual. Don’t forget the spare wheel!
10) Re-fasten the bolts after 5-20 km.
Et voilà, the tyre fitting is complete. However, there are reasons to carry out the fitting in a body shop. For example, if you have stored your tyres in a body shop, or if your tyres have an in-built tyre pressure monitoring system (TPMS). Then you’ll have to let an expert get down to work.