When installing a new tire, it’s a good idea to put the rim on a truing stand to measure radial runout. Check lateral runout at the same to ensure it’s withing 0.80mm. Radial runout is up and down variance from concentric. If the rim has, say 0.80mm or less radial runout, proceed with tire mounting. If there’s more than 0.80mm, a wire spoke rum needs to be re-trued to bring the radial runout within specifications.
A aluminum-alloy cast rim may need replacing depending on how far above 0.80mm the radial runout actually is. Most motorcycle companies advise replacement if radial runout exceeds 0.85mm. It is easy to instruct this, but not everyone has deep pockets with fat wallets, so compromise may same some money.
I do not get worried when replacing a rim for less fortunate customers until hitting 1mm radial runout. I explain the pros and cons and let the customer decide. However, if it goes higher than 1mm, then it becomes a safety issue in my mind, and I will dig my heels and refuse to re-install the rim.
After mounting the tire, check the radial runout once again. If up/down runout goes beyond 2.30mm, then it’s necessary to remount the tire. Tires are not as precise as metal rims. This is why the radial runout measurement climbs from 0.80mm on a rim to 2.30mm on a tire. If the tires radial runout stays at 2.30mm or more, the tire is defective and in need of replacement. A hopping tire will create vibration. I also check lateral or side-to-side tire runout.
Since the rim has already been checked for both radial and lateral trueness and is known to be good within 0.80mm, the tire should have a maximum lateral runout of 2mm. If this runout exceeds this amount, then remove and remount the tire. If a brand new tire cannot be withing the maximum lateral runout of 2mm replace the tire.
Unofficially it is said that about 5 percent of all tires manufactured are outside the maximum lateral runout of 2mm. In Europe, the US or most western countries this tires will be send back to the manufacturer and will be replaced In Thailand, it’s rare to see a mechanic to check the radial runout – they sometimes even skip the wheel balancing after replacing a tire...