Hey guys I have 19" tires on my car. They give a smooth ride on nice hwy roads and streets. But I noticed when I had my 18s on the car handled better obvisously, not that the 19s are that bad but i have Carrera Classics with 235/35/19 on the Front WO Spacers and 315/25/19 on the rears. My question is if I went w 7mm or 15mm spacers on the front and got 30 series tires on the rears instead of 25 series, would that make a big difference. Thanks for any input

 

235/35-19 will not work with 315/30-19 too much difference in circumference.

 

Sorry for confusion. It would be the 235/35/19 with 285/30/19

 

looks like those specs are tall...almost 2" more than reg stock 25"

PCA recommend %4 error between front/rear

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
235/35-19 3.2in 12.7in 25.5in 80.0in 792 0.0%
285/35-19 3.9in 13.4in 26.9in 84.4in 751 5.4%

235/30-19 2.8in 12.3in 24.6in 77.1in 821 0.0%
285/30-19 3.4in 12.9in 25.7in 80.8in 784 4.8%

edit:
This looks better:

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
235/35-19 3.2in 12.7in 25.5in 80.0in 792 0.0%
285/30-19 3.4in 12.9in 25.7in 80.8in 784 1.0%

 

Don't forget to take the measuring rim size into consideration for the specs posted by Redridge. If you put the 285 on the same size wheel as the 315, it will be a little stretched out (I'm assuming you're usind a 10.5 or 11 rear wheel).

Also, I'm not sure what you are really trying to fix by going to a narrower rear tire. Normally, performance handling is enhanced by a lower profile tire. The ride quality is worse. If you are trying to get a softer ride, changing the rear tire won't make a huge difference. You would either have to go back to the 18's or change the suspension.