NumanR
Established member
Hi Stuart, it is a really bad idea to change speed ratings on tyres for the following reason.
Tyres speed rating do not only refer to the maximum speed the tyre can spin up to. The speed rating is measured by the resistence to ballooning and is therefore a measure of the sidewall and carcass rigidity. Most vehicles are never used near their max speed rating BUT they are often used on hard acceleration where the sidewall comes under certain loads. The more power/torque you apply to the tyres the more they distort, this also applys to the tyre when braking hard. If you have a modified engine, then always fit the correct or higher speed rating of tyre.
Tyres speed rating do not only refer to the maximum speed the tyre can spin up to. The speed rating is measured by the resistence to ballooning and is therefore a measure of the sidewall and carcass rigidity. Most vehicles are never used near their max speed rating BUT they are often used on hard acceleration where the sidewall comes under certain loads. The more power/torque you apply to the tyres the more they distort, this also applys to the tyre when braking hard. If you have a modified engine, then always fit the correct or higher speed rating of tyre.