[Wunderkind]

I've been reading some reviews and comments that the Solstice' steering can be vague. I am wondering if this is because of the wide 245mm front contact patch.
So I've been noodling around with reducing the front tire width to a 225 foot print. However to maintain similar tire sizing, I will have to tweak the rear. I think given the GXP's torque, reducing to 225 is not a good idea. So I will match it with a 255/40 configuration. This results in 2.7% speedo change and a reduced sidewall.

It will increase understeer but I might get a sharper more responsive steering feel?

 

[phil1734]

Technically you are correct, but I've never heard of someone who was concerned with, or would even be able to notice the difference in steering feel who was also willing to sacrifice their ultimate grip level. If you are looking only at initial reviews and magazine test write-ups from when the Solstice was new it's also important to remember that these cars were delivered on notoriously horrible Goodyear tires.

I don't know the expectation you have for your car, but for most users here I would recommend the stock tire size but going a step or two more aggressive with tread and compound design, so look for a high performance all season or medium-performance summer. Compared to a regular all-season or touring tire they will increase both your steering feel and ultimate grip level far more than minute changes in section width, and you'll still be able to rotate them regularly to balance tread wear.

I've had 255/40R18s on my car the past two years and can also tell you that they look a little bit undersized. It's not obnoxious, but if you stare at it or catch just the right angle it looks like it skipped one too many leg days at the gym.

 

[JohnWR]

I think that most of @phil1734 's comments are spot-on, although I think the initial reports of steering issues were due to comparison with the lighter and twitchier Miata rather than the tires. That trivial point aside, i agree that your best move is better tires in the stock size.

The other change to make is to increase tire pressures by a couple of psi. I have found that 31-32 psi cold feels better than the stock 29 psi, but cannot completely rule out the difference being as much psychological as physical.

Have you actually experienced steering issues? I don't think I would make a change like this based on other people's perceptions, and I certainly would not deliberately induce understeer to improve "feel".

If I did have a good reason to make this type of change I would go to a 225/50 in the front, and leave the rears alone.

 

[Wunderkind]

Thank you both for your thoughtful comments. This is exactly what I want to validate against. I'll look into some summer performance tires to replace the Goodyear A/S. I have increased the tire pressures to 32 all around. Will continue to play around with that for a bit until I land on a good set of replacement tires.

@JohnWR , yes I am used to the livelier Miatas (owned NA, driven all models). My RX8 is also more fluid and active. Therefore the GXP steering felt less precise at turn ins or transition. It's good. Not the wooden feel of typical domestic cars. I think I'll refresh the power steering fluid too.

 

[07 Boss]

Another thing to think about besides tire compound and pressure is your alignment specs. I'm not versed on the intricacies of our suspension but here are some thoughts:

Most rwd cars have a slight toe in to compensate for suspension deflection during acceleration. A more neutral or toe out will decrease understeer and increase initial turn in. But you give up a little straight line stability and too much variance from stock may lead to a less stabile platform driving on uneven or slick conditions and also may lead to increases tire wear. It should be used as the last resort adjustment.

I have found that running a little extra negative camber has helped with cornering bite and initial turn-in with every single car I have driven. How far to increase negative camber has more to do with your driving style and aggressiveness. There is no magic number that works well for everybody. Again, too much negative camber decreases straight line stability and increased tracking/tramlining on rough roads.

Caster is one of those things that you only benefit from. Increasing caster, though it increases steering effort, only has plus sides when it comes to handling. It will increase straight line stability and also increase cornering effectiveness. Think about the front wheel on a bike and the caster of the forks. Keeps you straight when pointed forward and allows the tire to lean when turned. Only a manual steering car is going to be effected by the increased steering effort. I doubt you will feel any difference with power steering.

Just some food for thought when it comes to changing handling characteristics.

 

[JohnWR]

Most people I have talked to agree that the stock alignment specs work well for street driving.

Rear caster is something that can be a problem if the rear has been hit, or if it was aligned by somene who did not know what they are doing.

 

[Wunderkind]

Re: Alignment. I will look into it if/when I put on lowering springs or coilovers which is some time further down the road.

 

[07 Boss]

Most people I have talked to agree that the stock alignment specs work well for street driving.

Rear caster is something that can be a problem if the rear has been hit, or if it was aligned by somene who did not know what they are doing.

I agree that this car is pretty decent out of the box but suspensions are tuned pretty generically to suit all types of drivers and conditions. Granted you expect a little more aggressively for a sports car but still keeping the general public in mind. Just giving options to someone who looks like they want to do a little fine tuning to get the car to feel the way he wants. Deviating from factory specs always has downsides and one has to weigh the value on his own scale.

I was referring to front end alignment not the rear. I forgot this is an irs, I’m used to discussing solid axles.