Discussion
I have Avon cr66zz 275/55/r15 and 225/60/r15 at the rear and front respectively in my GT40 replica. I want to replace the badly worn (due to too much toe- out)fronts with part worn yoko A032r soft compound tyres as I did not want to pay £220 per tyre for the Avons. Is this combo going to be OK as I am going to a track day this week?,or do you pistonheaders frown upon tyre mixing.With the current Avons the car tends to understeer a little and if the Yokos are grippier than the Avon rears then this understeer will be reduced.
Does anyone have any experience of the two types of tyres with regards to grip levels?. I am trying to predict changes in the balance of the car.
Does anyone have any experience of the two types of tyres with regards to grip levels?. I am trying to predict changes in the balance of the car.
Well it won't necessarily mean trip to the armco.
Lotus themselves changes the tyre widths on the fronts (not compounds admittedly) on the Elise to reduce understeer when owners wanted a more neutral/oversteer setup. (The road cars were set up to understeer slightly as generally people were more used to it.)
So changing the compounds (and keeping the sizes) will affect the handling but its anyones guess by how much.
I have run normal size fronts 235/17 (D01J) and slightly smaller rears 265/18 (DunlopSS, should have been 285/18) and while the handling did induce oversteer it was manageable and, no, I didn't visit the ARMCO. Its all about gently managing the cornering until you are comfortable with the breakaway point. Of course it will change with compounds/sizes and you simply push gently until you reach the limit. Doing this on a safe section of track is sensible of course.
You are only changing compound which won't have the greater affect but will have some affect.
Take it easy and find the limit you are comfortable with
Best of luck
Lotus themselves changes the tyre widths on the fronts (not compounds admittedly) on the Elise to reduce understeer when owners wanted a more neutral/oversteer setup. (The road cars were set up to understeer slightly as generally people were more used to it.)
So changing the compounds (and keeping the sizes) will affect the handling but its anyones guess by how much.
I have run normal size fronts 235/17 (D01J) and slightly smaller rears 265/18 (DunlopSS, should have been 285/18) and while the handling did induce oversteer it was manageable and, no, I didn't visit the ARMCO. Its all about gently managing the cornering until you are comfortable with the breakaway point. Of course it will change with compounds/sizes and you simply push gently until you reach the limit. Doing this on a safe section of track is sensible of course.
You are only changing compound which won't have the greater affect but will have some affect.
Take it easy and find the limit you are comfortable with
Best of luck
unless you're driving something where the handling is of little or no interest then it's a bad idea. performance cars are developed assuming equal levels of grip between the 4 tyres and even a relatively minor change in grip levels can massively alter the balance of the car.
think of the efforts some people go to to make sure their pressures are correct on track - then think how pointless that is if the target/optimum grip levels are unachievable anyway due to a difference in tyre construction/compound/tread pattern etc
i've tried it a few times in the past when needs must but (assuming you're not a complete billy) you'll notice it pretty quickly. Even running different compound/hardness of the same tyre can cause massive handling imbalances.
in summary, don't buy a performance car and then compromise on the only part of the car that actually touches the ground.
Jonny
BaT
think of the efforts some people go to to make sure their pressures are correct on track - then think how pointless that is if the target/optimum grip levels are unachievable anyway due to a difference in tyre construction/compound/tread pattern etc
i've tried it a few times in the past when needs must but (assuming you're not a complete billy) you'll notice it pretty quickly. Even running different compound/hardness of the same tyre can cause massive handling imbalances.
in summary, don't buy a performance car and then compromise on the only part of the car that actually touches the ground.
Jonny
BaT
OP, how grippy are the Avons and how worn are the Yokos? If you have never used Yokos they are near enough cut slicks when new but do tend to fall off as they wear and get older and harder. They also tend to go off a bit after about 15 minutes at race speeds. I'd say you'd be OK with the 032s on the front as long as you can be sure they are good to use.
jleroux said:
unless you're driving something where the handling is of little or no interest then it's a bad idea. performance cars are developed assuming equal levels of grip between the 4 tyres and even a relatively minor change in grip levels can massively alter the balance of the car.
If you could find a definitive front and back tyre size i might just have agreed, but GT40s are rolling about on everything. It even looks like Ford themselves shifted about the rear tyre width significantly keeping the same fronts.
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