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[Saintor]

Originally Posted by captainaudio

Interesting.

I can't imagine that the roads in Montreal are in any better shape than the roads in NYC.

What tire pressures are you running on the 18" and 17"?

Are they RFTs"

CA

They are not RFT.

The quality of the my 18" tires doesn't seem to help neither. Over poor surfaces, my Yokohama w4s hit hard and became really noisy with mileage (a lot of people reported this on tirerack).

I always put 30psi everywhere and IIRC it is slighly under BMW 'recommendations in rear. Maybe I should put 26-28 psi on my 18"? Anyway even at this low pressure the wheels were damaged on 2 different occasions and it cost 88$ each to repair.



Never happened in 5 years with 17" before. So I tend to think that such low profile tires (18") are not compatible with our roads, much less the 19", presumably. I am now with my winter wheels 17" and it is almost heaven, challenging to believe that it is the same car/suspension. Those Vredestein Wintrac Xtreme are just quiet & smooth over all surfaces. So it is hard to fault the suspension, IMO.

[John 070]

Originally Posted by Saintor

They are not RFT.

The quality of the my 18" tires doesn't seem to help neither. Over poor surfaces, my Yokohama w4s hit hard and became really noisy with mileage (a lot of people reported this on tirerack).

I always put 30psi everywhere and IIRC it is slighly under BMW 'recommendations in rear. Maybe I should put 26-28 psi on my 18"? Anyway even at this low pressure the wheels were damaged on 2 different occasions and it cost 88$ each to repair.


Never happened in 5 years with 17" before. So I tend to think that such low profile tires (18") are not compatible with our roads, much less the 19", presumably. I am now with my winter wheels 17" and it is almost heaven, challenging to believe that it is the same car/suspension. Those Vredestein Wintrac Xtreme are just quiet & smooth over all surfaces. So it is hard to fault the suspension, IMO.

On my other car I've had 3 sets of 18's, 235/40-18. Each set had bent rims from seemingly innocent bumps. Not only that, even on rims that were not damaged, they tend to be out of balance as the tires age, and throwing them on a balancer where they check out, they still vibrated on the car.

I just went back to the stock rims, 215/55-16, and it is like total freedom now driving and parking. And at 85 mph the car is smooth as silk, no vibrations. 40 series look great, but they are just not practical in any way. And they don't really improve performance on a car that didn't come with them imho....there's probably a reason why the BMW OEM weighs nearly or 30 lbs.

[DnA Diesel]

I don't think trying to 'soften' a tire's ride by running lower pressure than the door jamb placard is a good idea. Running spec pressure and taking the ride as it is with whatever your particular suspension set-up is, should be the plan. Running lower pressures actually makes a tire and rim more susceptible to damage, not less. Does it feel like it's running a little harder, probably, but it's the suspension taking the force as it was designed, not the tire sidewall or the wheel. I realize ride quality is a subjective thing, but look at the difference in sidewall height between an 18 and a 17 and there really isn't a huge difference. Running the placard pressure is important for vehicle dynamics as well, in my younger mech eng days, I did a course dedicated to vehicle suspensions...you'd be amazed how the tires play a role in the overall dynamics of a vehicle, and how running components (like the tires, springs, struts) outside of nominal design parameters can adversely affect the vehicle dynamics. Also important for vehicles with DSC, ESP, etc... as the control algorithms are based on a certain set of design parameters that depend on the physical components behaving in real life the way they were programmed in to the control system. Not saying your car won't try to save when you push the limit and the DSC is engaged, but lower than spec tire pressures is one thing that could also adversely affect the vehicle's stability. Likely a stretch for most drivers, but you never know...every small little thing seems to add up when things go wrong, so just putting it out there that folks should think twice before they convince themselves to do something other than what hundreds of smart and capable German engineers designed into the vehicle. Food for thought.

Regards

[demosthenes]

Originally Posted by DnA Diesel

folks should think twice before they convince themselves to do something other than what hundreds of smart and capable German engineers designed into the vehicle

+1

Agree 100%. When the engineers designed, built, tested and tuned the suspension, braking, DSC and other systems, they used factory settings and components. When we change any of those elements, we risk knocking off the balance of the car.

I did it myself when I went from RFT's to PS2's. At first, I missed the great steering response the RFT's gave me but now that the PS2's have worn down, the steering response feels great again.

[stubenhocker]

Originally Posted by demosthenes

+1

Agree 100%. When the engineers designed, built, tested and tuned the suspension, braking, DSC and other systems, they used factory settings and components. When we change any of those elements, we risk knocking off the balance of the car.

I did it myself when I went from RFT's to PS2's. At first, I missed the great steering response the RFT's gave me but now that the PS2's have worn down, the steering response feels great again.

I agree wholeheartedly! It is laughable to see these guys question the wisdom of the factory setup. I recently switched my OEM Bstones with Continental RFT's and they seem to be better, at least they don't tramline!

[Neutrino45]

Originally Posted by stubenhocker

I agree wholeheartedly! It is laughable to see these guys question the wisdom of the factory setup. I recently switched my OEM Bstones with Continental RFT's and they seem to be better, at least they don't tramline!

So don't change rims as well?

[captainaudio]

Originally Posted by DnA Diesel

I don't think trying to 'soften' a tire's ride by running lower pressure than the door jamb placard is a good idea. Running spec pressure and taking the ride as it is with whatever your particular suspension set-up is, should be the plan. Running lower pressures actually makes a tire and rim more susceptible to damage, not less. Does it feel like it's running a little harder, probably, but it's the suspension taking the force as it was designed, not the tire sidewall or the wheel. I realize ride quality is a subjective thing, but look at the difference in sidewall height between an 18 and a 17 and there really isn't a huge difference. Running the placard pressure is important for vehicle dynamics as well, in my younger mech eng days, I did a course dedicated to vehicle suspensions...you'd be amazed how the tires play a role in the overall dynamics of a vehicle, and how running components (like the tires, springs, struts) outside of nominal design parameters can adversely affect the vehicle dynamics. Also important for vehicles with DSC, ESP, etc... as the control algorithms are based on a certain set of design parameters that depend on the physical components behaving in real life the way they were programmed in to the control system. Not saying your car won't try to save when you push the limit and the DSC is engaged, but lower than spec tire pressures is one thing that could also adversely affect the vehicle's stability. Likely a stretch for most drivers, but you never know...every small little thing seems to add up when things go wrong, so just putting it out there that folks should think twice before they convince themselves to do something other than what hundreds of smart and capable German engineers designed into the vehicle. Food for thought.

Regards

I bought a 335i with Sport Package in Palm Beach Florida. I had no issue woth the RFTs in that environment. After I shipped the car to NYC it was a totally different story. The car was for all practical purposes undriveable here.

I posted my concerns here and it was suggested that I replace the RFTs. I got rid of them with less than 2.000 miles on them and the difference was huge. I replaced them with Pirelli P_Zero Nero M&S All Seasons and found them superior in every way to the original Bridgestone RFTs which I have to rate as absolutely the worst tires I have ever had.

The car was still a PITA over rough surfaces and I was still getting "Pothole Explosions". A few weeks ago I inflated the tires to 38 PSI front and 40 PSI rear. Although this is counterintuitive I found that the car did much better over rough surfaces with the higher pressures. At first I thought this was Placebo Effect but my wife feels the same way.

CA

[demosthenes]

Originally Posted by captainaudio

A few weeks ago I inflated the tires to 38 PSI front and 40 PSI rear. Although this is counterintuitive I found that the car did much better over rough surfaces with the higher pressures. At first I thought this was Placebo Effect but my wife feels the same way.

Very interesting. Do you have any ideas on why increasing tire pressures helped? What pressures did you have before increasing them? Thanks.