I got an 07 G35 sedan journey with the 18 OEMs rims,so 18x7.5 in the front, 18x8 in the back.
front supposed to be 225/50/18 while in the back is supposed to be 245/45/18.

But i am running 245/45s front and back, and you can feel almost everything in the road, and the car rock sometimes.

had the tires balanced, dealer has checked the suspension, but they keep telling me that's the tires. i need to get 225/50s in the fronts since it's throwing off the computer, and that's what is sometime causing the bumpiness of the ride.

they are saying that it's kinda throwing the computer off, so the rear tires spin a little faster when i step on the brakes or something like that.

What you guys think? is this possible?

i dont' think a computer can affect ride quality

 

245/45 18s all around should NOT throw off the computer (I believe the computer only controls ABS and traction control system, not ride quality anyway). Computer is happy if all 4 tires have the same tread diameter (Journey w/17 in. wheels has all tires the same diameter). You do not have to run 225/50s in front, but the slightly taller sidewall may soften the ride a little.

May also want to consider 235/50s in front and 255/45s in back, the taller side walls may help. "Touring" tires may also ride softer than hi perf. tires. but would sacrifice handling.

 

That sounds like a load of bs from the dealer. You could try running a little lower pressure on all four corners, it's cheaper than new tires.

 

The sidewall on the 225/50 is the EXACT same size as the 245/45

 

ya, rolling size is the same, tell the dealer to blow it out there *** and fix ur car,

 

I have an 09 G35XS. In my opinion the 225 50's are too narrow. Tire Rack recommended the 245 45's. Be sure that your tires are properly inflated and the alignment is ok. High performance tires will give you a more agressive ride and you will feel everything on the road.

The trade off comes when cornering and manuvering the larger tires are the way to go. Different makes of the same size tend to ride differently, as do summer vs all season tires.

Ride comfort is personal. Enjoy

 

these cars ride firm.

get a lexus.

 

yep now i know.

 

yeah i dont' think a computer would mess the ride quality neither

but i guess i would just buy 225/50s or 235/50s in the front (n keep the 245/50s in the back for now) cuz every time i take it they tell me the same thing. at least this way i would increase the sidewall also.
Plus, i have 25,000 more miles to go for the warranty

but is it ok to run two different set of brands in the car? fronts would prob be michelin or pirelli while the backs woudl be yokohamas

 

If it were me I would not run two different brands on the car. The tread designs are different and will change the way the car handles.

I have a 2005 S4 with 235 40s on all 4 corners. The car originally came with summer tires and I switched to all season for the winter. Yes the car is stiff, but the grip is very enjoyable.

 

3-4 psi makes huge different. I'd try to go lower on the pressure. What is the pressure?

 

i think it was 33psi usually.

the dealer put 36psi according to the paperwork. it made have made a difference.

would higher or lower pressure make it softer?

 

Be very careful believing anything the service writers tell you, it's based on his/her opinion not fact. Run whatever tire pressure the manual tells you to run + or - 2 lbs. I run 37 on all four corners, my tire shop wants to run 40 lbs which is dumb and makes my coupe feel like it's riding on rocks....and wears out the centers of my tires. Oh yea, they sell tires!
Gary