I am ex-tyre manufacturing and I posted this in a previous thread on this subject. I am happy to use Vredestein Sprint Classics on my current 4/4 and previously used them for road, hillclimbs and production car trials without problems.
"Sidewall bulges and hollows are a function of the way in which the sidewall is applied during the tyre building process. In manual tyre building the sidewalls are applied to a horizontal drum and joined (or spliced) butt, or with a specified amount of overlap. If the overlap is too large it can cause a bulge at the join and a hollow in the area immediately behind the join.These are normally cosmetic defects and will not affect the performance of the tyre. Bulges which are caused by structural damage which results in spreading of the ply cords on the other hand, are dangerous and any tyre which has this damage should be replaced immediately.
Tyres which are supplied to car manufacturers as original equipment (O/E) have to meet the car manufacturers' specification for sidewall undulations and tyre manufacturers employ sophisticated measurement equipment during the final inspection phase of the tyre manufacturing operations to check this.Since the type of tyres we are talking about are not used as O/E I will leave you to draw your own conclusions............"
