Well thanks to TGTT advice on earlier posts my Sera has finally ditched the 17's
That is 17x7x40 offset Rims 9.98kg 205/17/40 tyres ( 580 Dia ) now 15x7x38 offset Rims 5.85kg 195/15/50 Tyres. Total old 18.14kg vs new 13.63kg Weight saving 4.51kg ( 9.94lb )/ wheel
This gives improved comfort, braking and acceleration but a few other things also happened -
Acceleration
- Car moves off the mark easier I dont have to wait for the wheels to rotate before I can accelerate hard.
- Acceleration is more responsive but still need to change back from overdrive to accelerate quickly but overdrive is generally more useful.
- Boost feels different the torque increase makes the car feel like it is boosting sooner but it is just accelerating more at the same boost.
Noise
- I can still feel every bump but the bumps are dampened like punching a timber floor through carpet rather a concrete one.
- Road Rumble is significantly quieter a better driving experience.. I'm told noise will increase as the tyre wears, unless I buy softer tyres.
Handling
- Handling on curves over ruts is more sure footed the car does not slip side ways as before.
- Turning is worse for quick pointing. It seems I have to turn the wheel further before the car responds from straight line driving.
- Turning tight corners at speed the car can feels a little floaty compared to before.
- Lighter steering turning from stationary and Sharp turning from stationary at 90 degs is better the car does not want to go sidways.
- Suspension is quicker so I can now go faster over speed humps with less jumping of the back of the car.
Gears
- Auto gear changes appear more frequent as load difference is sensed by the auto box and convertor lock up point may have changed.
- One negative is the box now wants to change to OD while I am accelerating hard. This results in a huge loss of power as there is a mismatch with the gear box that stalls the engine. It feels like fuel cut and can be dangerous if overtaking or going hard up a hill.
Throttle
- Throttle control is much more tiring on the driver as gears are changing more and you need to be properly match throttle to speed.With the heavier wheels it was more point , shoot and brake style driving.
Brakes
- Braking is much improved. I don't have to dwell on the brakes as much and hold the brake pedal contantly down hills.
- Can now use the throttle to slow the car when cruising. I can stop the car on the spongy part of the pedal travel before refusal.
Further testing in the wet TBA
- Under steer or over steer
- Turning at speed down wrong cambered hill
- Round-about skidding
Fuel consumption difference TBA.
That is 17x7x40 offset Rims 9.98kg 205/17/40 tyres ( 580 Dia ) now 15x7x38 offset Rims 5.85kg 195/15/50 Tyres. Total old 18.14kg vs new 13.63kg Weight saving 4.51kg ( 9.94lb )/ wheel
This gives improved comfort, braking and acceleration but a few other things also happened -
Acceleration
- Car moves off the mark easier I dont have to wait for the wheels to rotate before I can accelerate hard.
- Acceleration is more responsive but still need to change back from overdrive to accelerate quickly but overdrive is generally more useful.
- Boost feels different the torque increase makes the car feel like it is boosting sooner but it is just accelerating more at the same boost.
Noise
- I can still feel every bump but the bumps are dampened like punching a timber floor through carpet rather a concrete one.
- Road Rumble is significantly quieter a better driving experience.. I'm told noise will increase as the tyre wears, unless I buy softer tyres.
Handling
- Handling on curves over ruts is more sure footed the car does not slip side ways as before.
- Turning is worse for quick pointing. It seems I have to turn the wheel further before the car responds from straight line driving.
- Turning tight corners at speed the car can feels a little floaty compared to before.
- Lighter steering turning from stationary and Sharp turning from stationary at 90 degs is better the car does not want to go sidways.
- Suspension is quicker so I can now go faster over speed humps with less jumping of the back of the car.
Gears
- Auto gear changes appear more frequent as load difference is sensed by the auto box and convertor lock up point may have changed.
- One negative is the box now wants to change to OD while I am accelerating hard. This results in a huge loss of power as there is a mismatch with the gear box that stalls the engine. It feels like fuel cut and can be dangerous if overtaking or going hard up a hill.
Throttle
- Throttle control is much more tiring on the driver as gears are changing more and you need to be properly match throttle to speed.With the heavier wheels it was more point , shoot and brake style driving.
Brakes
- Braking is much improved. I don't have to dwell on the brakes as much and hold the brake pedal contantly down hills.
- Can now use the throttle to slow the car when cruising. I can stop the car on the spongy part of the pedal travel before refusal.
Further testing in the wet TBA
- Under steer or over steer
- Turning at speed down wrong cambered hill
- Round-about skidding
Fuel consumption difference TBA.
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