Hello everybody!
I have a question about tires on stock rims saab 9-5 sport combi with aero package (SPORT SUSPENSION).
My stock tires 235/45/17 on anniversary rims and they kind of not comfortable on any small uneven surface or bump,and sometimes giving me harsh ride.
I'm thinking to put 235/55/17,so ride would be a little more comfortable.
if anyone familiar with sizes and specs please reply!
thanks in advance!!

I wouldn't change from the standard specified tire size. While there may be a very small improvement in comfort, it will hardly be noticeable.

What tires do you currently have? I noticed a big difference between tire brands and types when it comes to comfort. Tires sometimes also get louder and less comfortable when they wear down so that may be the issue with your current tires as well. I had some pretty worn 17" Goodyear high performance 17" tires and changing to Yokahama's (more of a touring tire) made a big difference in noise and comfort.

Your problem is the sport suspension - sport means hard. If you didn't like a harsh ride, that was not the right suspension package to opt for. It's a give and take on the "now old" 9-5's. The current generation offers you selectable suspension and power options so you can have it when you want it. Sorry - nothing tires will change for the better. The 235/45/17 is the best size for the application IMHO. You could try a 225/45/17 - it was the older stock size. Less width, but same % of height. Less road surface to bang on....

I would tend to agree with WULF however on the BRAND of tires. There is MUCH to varry there which COULD make your ride a little more comfortable.

Originally Posted by jass80

Hello everybody!
I have a question about tires on stock rims saab 9-5 sport combi with aero package (SPORT SUSPENSION).
My stock tires 235/45/17 on anniversary rims and they kind of not comfortable on any small uneven surface or bump,and sometimes giving me harsh ride.
I'm thinking to put 235/55/17,so ride would be a little more comfortable.
if anyone familiar with sizes and specs please reply!
thanks in advance!!

235/55r17 is out of specification, too much diameter
the thread high is the percent of thread width per profile
total tire diameter = (235x55%)x2+(17"x25.4)
see tires equivalences:
Tire Size Calculator - tire & wheel plus sizing
Tire Size Calculator

You could go down to 16 inch, that would give you more rubber between road and rim. But maybe you should look into changing to stock suspension instead? I've heard that progressive springs like Hirsch can improve the harshness, which seems to have become some kind of a Saab trademark...

I agree with Wulf.
Look to change the tire ... it can be one of the most dramatic changes anyone can make to a car.

Look at Michelin.
I have the Pilot Sport A/S+ on my 9-5 and the ride is incredible, compliant, quiet, very grippy, and not too harsh at all.

Hello everybody first of all thanks for advices !
I'm thinking to get set of new OEM struts and shocks, and probably newer and softer tires.
Anyone can tell me what else need to be changed since sport susp becomes regular?
May be springs need to be replaced as well? i hope not!
And what is the best trustful source on internet to get from?
thanks!

Originally Posted by jass80

Hello everybody first of all thanks for advices !
I'm thinking to get set of new OEM struts and shocks, and probably newer and softer tires.
Anyone can tell me what else need to be changed since sport susp becomes regular?
May be springs need to be replaced as well? i hope not!
And what is the best trustful source on internet to get from?
thanks!

I regret to say a negative answer ....... may you ask to your dealer if these modifications can be done for a sporty suspension.
sport chassis involves many parts (brakes, springs,.. modules ABS/TC/ECB/ESP....) and different software for the modules.

with the soft suspension you will feel dizzy in the mountain roads...

Originally Posted by jass80

Hello everybody first of all thanks for advices !
I'm thinking to get set of new OEM struts and shocks, and probably newer and softer tires.
Anyone can tell me what else need to be changed since sport susp becomes regular?
May be springs need to be replaced as well? i hope not!
And what is the best trustful source on internet to get from?
thanks!

As jlrdrony said, the sport suspension has many parts, but the ones that will change it to the ride you want include: springs, shocks (those are the biggest two!), and I also believe that struts and anti-roll bar are part of the sport suspension. Those change the dynamics of the ride, but effect the corning of the car more than the ride over bumps and what-not. If I were you, I'd start tires, see where that gets you, then go to springs, see where than gets you, then shocks.... you get the idea. Though you probably get a price break if you order the springs and shocks together.

I think if after changing tires (I agree with Shazam that it should be the first thing you do), you find that the car is still too harsh a ride for your taste, the easiest option would be to trade it in against another 9-5 without the sports suspension.
The amount of money you would spend softening the suspension would not be worth it.
You would also have a hard time selling the car when you are done with it ...

"Yes, I know it says "Aero" on the car, but I changed out the suspension to base. So you get some of the Aero bits, but not the parts to keep the car firmly planted to the road."

Originally Posted by jass80

Hello everybody!

I'm thinking to put 235/55/17,so ride would be a little more comfortable.
if anyone familiar with sizes and specs please reply!
thanks in advance!!

the nearest equivalence is 225/50R17 see
Why The Different Tire Sizes on Aero XWD?
but not allowed in Spain, not sure in The US.

Hi guys, my tires are Fierce Instinct ZR 235/45/17 , and seems like they're cheap ($104 a piece) compared to Michelin and some other good known tire brands.Anyone known with Fierce instinct tires?
Last night i found Michelin pilot mxm4's, for $204 a piece and plus $94 road hazard = $910 and tax!
Another option was with "Pepboys" guys 16" rims plus Futura touring HR tires 225/55/17 plus balance,and alignment for $1058!
I need to mention that the Michelin tires i mentioned above can be either 235/45/17 or 235/50/17 sizes,if 235/50/17 would fit
i think that probably would be significant improvement on ride comfort!!???
Would 235/50/17 tires affect some computer info beside
wrong speed readings?

Originally Posted by jass80

235/45/17 or 235/50/17 sizes,if 235/50/17 would fit
i think that probably would be significant improvement on ride comfort!!???
Would 235/50/17 tires affect some computer info beside
wrong speed readings?

Original tire 235/45R17
Sidewall: 4.16 in
Radius: 12.66 in
Diameter: 25.33 in
Circumf: 79.57 in
Revs/mile: 796.32

New Tire 235/50R17
Sidewall: 4.63 in
Radius: 13.13 in
Diameter: 26.25 in
Circumf: 82.47 in
Revs/mile: 768.25


Speedometer reading with new tire is 3.65% too slow.
When your speedometer is reading 60mph you are actually traveling 62.11mph.

Warning! When changing tire sizes, recommended staying within 3% of the diameter of the original tire. Any more than this and you face the risk of brake failure.

You have a factory Sport suspension so I think you are going to have a stiff ride unless you go to smaller rims with taller tires. IMO I wouldn't do it but it is your car. Good luck.

the sidewall, profile has a relation with the rim width:
for i.e.
235/45R17 rims 7.5" x 17 you cann't use 50 profile in sport chassis due to the rims specifications.
225/50R17 rims 7" x 17