Iceman
Member
Right i have had the 33" Cooper ST MAXX tyres on for a week or so and done around 2000km so far.
I was a little worried as to how they would affect the overall performance of the vehicle so i have drawn up this wee list of how you can expect them to alter your D40 too. I have a thai built 126kw dual cab ST 2010 auto.
You will need at least two inches of lift and 45 offset wheels. Stock on this model. Mine just touch the chassis at the rear of the front. Not enough to worry about just dont drive hard in reverse on full lock.
Power - as the tyres are a larger diameter 841mm they are harder for the engine to turn. Effectivley reducing the final drive ratio. This reduces the amount of power available. My 'seat o the pants' meter says approx 10% loss. This may not sound alot but it is noticable, especially on hill climbing or overtaking. It looses the "punch" in the acceleration. A slight adjustment in driving style is needed. I would assume they would work a bit better on a manual where you have better control of the revs in the torque band.
This could be offset by putting in higher ratio diffs to bring it back to a near stock final drive ratio, i wouldnt bother unless i got them cheap.
Engine braking is reduced by the same amount as the wheels have more "turning force" being bigger.
Odo - due to the larger rolling diameter the odo will now read under the actual distance travelled. In my case by exactly 12%. This means your truck will show less ks than it really has (oh well!)
Speedometer - my speedo was always a bit optomistic and the 33s have brought it bang on. Its better than 1% now
Handeling - the tyres are alot heavier than the stock ones and add alot to the unsprung weight. You can really feel this at higher speed on an uneven surface. You will at the very least need good shocks and springs. The stock ones really are not up to it. I replace mine with monroe shocks, dobinson coils and ironman leaves, all 2" raise. The steering is heavier due to the larger footprint and extra leverage required to move the larger tyre on the road, by the same effect the road has more effect on the steering due to the greater leverage. Its not alot but requires driving style changes. The road will pull you around more and ther is a little less self centering force. The grip is awsome! Cornering is fantastic compared to the stock rubber. Roadholding on loose surfaces is unreal.
Brakes - this is perhaps the most significant change. The brakeing is reduced. Not by a huge amount, i would say by about 10%, but it is right when you need it in the zone at lower speed when you need to scrub off as much speed as fast as possible. It will still just activate the abs but the stopping distance is longer. Its like trying to stop with a load on board, there just isnt the same bite to the brakes. This will be the first thing i will be attempting to mitigate. I do have the smaller brakes with the 16" wheels so cant really upsize the rotors. Braided lines and upgraded pads to start with i think.
Fuel consumption - the car will use more fuel. Larger tyres are harder to turn so more power needed means heavier right foot equals more gas. The difference is not huge. In my car it was 1 ltr per 100 km. it went from 13/100 to 14/100 exactly. This is real distance not taken from the inacurate odo. Considering i had a 250kg load and a MCC bullbar i thought this was pretty good. Improved driving style could help alot here by letting the engine do the work rather than blasting up hills etc.
A diff change would bring this back to original level. Even though the engine would be revving a little higher it would be in the torque band and more efficient more of the time. My 100kph cruising revs have gone from 2100rpm to 2000rpm as the car is now effectively taller geared
I guess the 140kw engine owners will have a better time.
Driving forces are higher on the transmission, especially in 4wd, axle bind is more obvious due to the increased traction.
So overall its really swings and roundabouts, you gain 12% on road mileage, use 1/100 more gas, have a bit less power, a more comfortable ride, much better grip, slightly reduced driveability, increased ground clearance, lower revs.
Would i do it again. Sure would!
Lots of the downsides can be easily mitigated. Water/meth injection for a bit more power and lower egts, a better intercooler and hard pipe conversion, a bit more boost and fuel, better zorst and better driving.
Well thats about it so far, any thoughts? Whats your experience been with 33s?
I was a little worried as to how they would affect the overall performance of the vehicle so i have drawn up this wee list of how you can expect them to alter your D40 too. I have a thai built 126kw dual cab ST 2010 auto.
You will need at least two inches of lift and 45 offset wheels. Stock on this model. Mine just touch the chassis at the rear of the front. Not enough to worry about just dont drive hard in reverse on full lock.
Power - as the tyres are a larger diameter 841mm they are harder for the engine to turn. Effectivley reducing the final drive ratio. This reduces the amount of power available. My 'seat o the pants' meter says approx 10% loss. This may not sound alot but it is noticable, especially on hill climbing or overtaking. It looses the "punch" in the acceleration. A slight adjustment in driving style is needed. I would assume they would work a bit better on a manual where you have better control of the revs in the torque band.
This could be offset by putting in higher ratio diffs to bring it back to a near stock final drive ratio, i wouldnt bother unless i got them cheap.
Engine braking is reduced by the same amount as the wheels have more "turning force" being bigger.
Odo - due to the larger rolling diameter the odo will now read under the actual distance travelled. In my case by exactly 12%. This means your truck will show less ks than it really has (oh well!)
Speedometer - my speedo was always a bit optomistic and the 33s have brought it bang on. Its better than 1% now
Handeling - the tyres are alot heavier than the stock ones and add alot to the unsprung weight. You can really feel this at higher speed on an uneven surface. You will at the very least need good shocks and springs. The stock ones really are not up to it. I replace mine with monroe shocks, dobinson coils and ironman leaves, all 2" raise. The steering is heavier due to the larger footprint and extra leverage required to move the larger tyre on the road, by the same effect the road has more effect on the steering due to the greater leverage. Its not alot but requires driving style changes. The road will pull you around more and ther is a little less self centering force. The grip is awsome! Cornering is fantastic compared to the stock rubber. Roadholding on loose surfaces is unreal.
Brakes - this is perhaps the most significant change. The brakeing is reduced. Not by a huge amount, i would say by about 10%, but it is right when you need it in the zone at lower speed when you need to scrub off as much speed as fast as possible. It will still just activate the abs but the stopping distance is longer. Its like trying to stop with a load on board, there just isnt the same bite to the brakes. This will be the first thing i will be attempting to mitigate. I do have the smaller brakes with the 16" wheels so cant really upsize the rotors. Braided lines and upgraded pads to start with i think.
Fuel consumption - the car will use more fuel. Larger tyres are harder to turn so more power needed means heavier right foot equals more gas. The difference is not huge. In my car it was 1 ltr per 100 km. it went from 13/100 to 14/100 exactly. This is real distance not taken from the inacurate odo. Considering i had a 250kg load and a MCC bullbar i thought this was pretty good. Improved driving style could help alot here by letting the engine do the work rather than blasting up hills etc.
A diff change would bring this back to original level. Even though the engine would be revving a little higher it would be in the torque band and more efficient more of the time. My 100kph cruising revs have gone from 2100rpm to 2000rpm as the car is now effectively taller geared
I guess the 140kw engine owners will have a better time.
Driving forces are higher on the transmission, especially in 4wd, axle bind is more obvious due to the increased traction.
So overall its really swings and roundabouts, you gain 12% on road mileage, use 1/100 more gas, have a bit less power, a more comfortable ride, much better grip, slightly reduced driveability, increased ground clearance, lower revs.
Would i do it again. Sure would!
Lots of the downsides can be easily mitigated. Water/meth injection for a bit more power and lower egts, a better intercooler and hard pipe conversion, a bit more boost and fuel, better zorst and better driving.
Well thats about it so far, any thoughts? Whats your experience been with 33s?