Loving runflats

‘ Runf lat’ bec ame a derogator y term in the early ’ 00s when BMW adopted such tyres for a va st por tion of its range. The M division refused to use them and owners quickly replaced them to avoid the brittle ride quality. Runf lat tech, in its early mainstream applic ation, wa s considered A Ver y Bad Thing.

I wa s of that opinion before I visited Bridgestone’s test facilit y near Rome back in 2006. Then they strapped me into a 3- series and a sked me to drive at 60mph around a long cur ve that mimicked a motor way sweeper. Half way round, a simulated blowout made the BMW spin wildly. The same test with a runf lat barely changed the c ar’s trajector y, and I pulled up without fuss. Runf lats seemed a pretty good idea .

A dec ade later I’m back at Bridgestone’s proving ground and a man hammers a five- inch nail into the shoulder of a new runf lat c alled ‘ Driveguard’. The tyre def lates and I hop in the Golf for a drive. These tyres are still heavier than normal tyres – by 7 to 20 per cent – and they still feature a stif fer sidewall structure to suppor t the weight of the c ar. However, Bridgestone claims they do not need a dedic ated cha ssis setup. It ha s also added cooling fins, which increa se durabilit y and allow you to drive 50 miles at 50mph on a compromised tyre.

The Golf drives almost a s normal, just with the odd squeak from the f lat tyre and pulling slightly to the lef t. It’s remarkable. We need to test the Driveguard system more fully and a gainst conventional rubber, but the runf lat concept isn’t going away and it appears that the benefits are star ting to outweigh the drawbacks.