Run-flat tyres: extra weight

The fourth nuance: extra unsprung mass. It is obvious that the extra sidewall stiffness is achieved, among other things, by thickening the profile. More rubber compound means more tyre weight (and we are not talking grams here - the difference is measured in kilograms, which is already quite noticeable). The result: more load on the suspension and worse handling. How much worse all this gets compared with an ordinary tyre depends heavily on which specific tyres are chosen for the comparison, but all else being equal it will definitely be worse. All the tyre makers’ advertising claims that they have supposedly narrowed the gap in performance against ordinary tyres down to an unnoticeable minimum are mostly based on a “convenient” choice of tyres for the comparison.