Z4 Tire Selection Help for 19" rims

[rgeorge12]

I have a 2003 2.5L Z4 Roadster and I need to buy some new tires. I bought this car with the tire and rims already installed. I have 19" giovanni rims but I'm there is terrible!!!!!! road noise. The tires on my car are a brand called "Sunny" never heard of them and the size for the front and back are 245/35.

My mechanic recommends i get all new rims and tires? He says the rims are to big for the car?.... that really did not sit right with me considering the giovanni rims look good and are expensive.

I have been looking at some forums here and there. I found that the best size tires for 19 inch rims are: Rear 255/30 & Front 235/35 ? Can anyone confirm this or have any advice? I was also looking at getting Continental DWS tires...has anyone tired these out before? It look like they are the best bang for the buck review wise?

Here is the car

[mitchsf]

Can't help with the rims or sizes, but have you considered DW, since we really don't need all weather tires down here in hot hell. I just put a set on and I'm happy so far, although I don't push them anywhere near their limits.

[-c-]

i bought the Nitto Invos and their quiet as all getout! looks bad ass as well.....

[pokeybritches]

I agree with your mechanic regarding wheel size on the non-M Z4. 19's are heavy, unnecessary, and there isn't enough sidewall to adequately cushion against wheel damage. They ride poorly... unless they are so heavy that the lack of response translates into a smoother ride, in which case performance is severely degraded. Tires are more expensive. The only reason to go with 19's on a non-M is aesthetics, and some would argue they dwarf the brake rotors and create a huge gap between rotor and wheel. You can get away with 19's on a Z4M because the tire diameter is larger (more sidewall).

As far as tires go- 225/40/18 (225/35/19) front; 255/35/18 (255/30/19) rear. Michelin Pilot Super Sports if you can afford them, Sumitomo HTR Z III if you are more worried about price and daily driving.

[-c-]

Originally Posted by pokeybritches

You can get away with 19's on a Z4M because the tire diameter is larger (more sidewall).
.

again i went with a taller tire than stock to aleaviate the issue, tire size can be all over the map and Z4M would have nothing to do with it as the wheel wells are the same between the M and non M Z4 so it comes down to wheel and tire pakage you go with.

my tire size is 235, 35, 19 front and 265, 30, 19 rear, ride is still smooth and no jarring feelings going over bumps.... mine is also a non M and came stock with 17" wheels.

im running a thicker tire than the stock setup on a 2011 Z4 with 19" wheels, or at least thats what my last visit to the dealer told me.

[pokeybritches]

The difference is an M is calibrated for the larger diameter tires while a non-M is not. There is a difference of about 4% between 255/35/18 and 255/40/18 (or 255/30/19 and 255/35/19). A 2.5i would drive like it's down about 7 hp, and the speedometer and odometer would both read low (though it's arguable the speedo isn't accurate in the first place)... not to mention added rotational inertia and unsprung weight. 265/30/19 tires are only about 1% off, but they also only have about 0.15" of extra sidewall. OP also has the 2.5i's smaller brakes. My opinion is OP should ditch the 19's in favor of some lightweight 18's.

Originally Posted by -c-

again i went with a taller tire than stock to aleaviate the issue, tire size can be all over the map and Z4M would have nothing to do with it as the wheel wells are the same between the M and non M Z4 so it comes down to wheel and tire pakage you go with.

my tire size is 235, 35, 19 front and 265, 30, 19 rear, ride is still smooth and no jarring feelings going over bumps.... mine is also a non M and came stock with 17" wheels.

im running a thicker tire than the stock setup on a 2011 Z4 with 19" wheels, or at least thats what my last visit to the dealer told me.

[-c-]

Originally Posted by pokeybritches

The difference is an M is calibrated for the larger diameter tires while a non-M is not. There is a difference of about 4% between 255/35/18 and 255/40/18 (or 255/30/19 and 255/35/19). A 2.5i would drive like it's down about 7 hp, and the speedometer and odometer would both read low (though it's arguable the speedo isn't accurate in the first place)... not to mention added rotational inertia and unsprung weight. 265/30/19 tires are only about 1% off, but they also only have about 0.15" of extra sidewall. OP also has the 2.5i's smaller brakes. My opinion is OP should ditch the 19's in favor of some lightweight 18's.

ahhh the gearing sorry pokey!, i got you! tee hee ! i was thinking just volume and not mechanical my bad... also didnt realize it was the 2.5 so yea bigger heavier wheels will be felt for sure...

im getting that ecu tuned to offset the bigger tires and wheels, or maybe i should just change my gearing all together ....... hmmmmmm that may be fun!



man its been a long day i need some sleep !

[pokeybritches]

Let me know what gearing you go to! I bought a 3.64 off a 2.5i auto that I may swap in. I'm considering going to the same diameter tires in 18's (265/35/18). I'm also pretty interested in the ECU reprogram and what that entails.

[CJW2OO4]

I am running 235/35/19 front and 275/30/19 rears on my non m coupe. I am lowered though... not sure if I could use a tire that wide on factory suspension.