I'm curious as to whether any of have gone to different sizes of tires from front to rear.

I'm stiffening the rear with a 22mm sway bar and I expect that the rear could get a little loose. Accordingly, I've been wondering if there might be an advantage to a larger patch in the rear, perhaps 205 in front and 215 in the rear.

I've even wondered - since I'll probably be looking for wheels eventually, if anyone had gone to 16s in the front and 17 in the rear with perhaps a 55 section width in front and a 45 in the rear.

I realize, of course, the issues with rotating tires, but if that is offset by improvements in handling, it may be worth it.

Has this been considered by anyone?

 

If you go that route you are going to give the ABS & DSC nanny a migraine. Personally I don't see a problem with your cars handling with a 22mm rear bar.

 

Many do it but not for handling.... they do it for the 9" wide rim out back w. a 8" up front, stretched usually

 

As they say different strokes...

 

What are you trying to acheive? Most put rear sway to acheive oversteer (the rear to come out) for faster (and flatter) turns. Some even unfasten the front bar to acheive this. Rear rotation is a good thing for tight turns and for even sweepers if you are brave or experienced. I have a 25.5 hollow bar in the rear and to get even more rotation I put a higher psi in rear tires. Inversely, you could achieve the same by playing with the rear tire pressure til you get stock (slight understeer) charachteristics or lower psi for more nuetral handling. And no need to do all that wacky differnt wheel and goofy tire sizes, just 215/40-17 all around.

 

Thanks folks -- I hadn't considered the effect on ABS or any of the other systems. I want to achieve a controlled neutral handling car. I really find wa to much understeer and was looking at tightening the sway bar a lot then controlling twitchiness with an increased contact patch.

It looks to me like I would be better served by playing with the sway bar and leaving the tire size alone.

I'm still debating whether or not to go to 17 inch wheels. I have the 16 Bridgespokes. They are not terribly heavy (about 21 lbs with the tpms in place). Most of the 17s that I've looked at are around 23, and of course, the 17 inch tire will outweigh the 16s. I want to keep unsprung weight to the minimum, of course, but I'm also a bit concerend about the impact of 50 vs 55 vs 45 section width on the overall gear ratios.

Remember, I have an automatic Justa so I have to maximize the chassis, not the power.

I really want to go to an increased section width, hence the consideration of 205/55x16s vs the 205/50s. But the 50s would result in a slightly lower overall gear ration (more rpm per mph) while the 205/55s would give a slightly higher ratio (in my mind, that is also undesireable because it may place the rpm too low in the torque band). I'm also concerend that going to 205/45/17s will improve my contact patch at the expense of requiring more power to get them spinning.

Ahh. The fun of playing with cars.

 

Put that rear swaybar on & go with a set of camber plates up front. Then get a good alignment. 21 pounds is a heavy wheel. You can get lighter ones & it will help acceleration, handling & braking.

 

OP, Also, spend some time defining what you mean by neutral handing and what it feels like in the car. I think it is an ellusive concept.

 

Your fine with sway on soft setting then just play with tire pressures. Later try out hard setting and adjust psi to get it to your definition of nuetral. Lightweight 15x7s like Kosei K1 TS (12.6lb) on 205/50-15 will better serve a JustaCooper.