Advice on my M

[Scholarjahh]

I own a 2007 m35x just want to know what's the best size rims to upgrade. Also wanted to know if the gears switching while I drive should be heard while I hit the gass on automatic .

[Ilya]

19's or 20's.

Hearing gears should not be happening.

[svard75]

Ilyakols right on but I wanted to throw in some things to think about regarding wheels. What is your goal? Do you want it to look cool or do you want it to ride smoother? Wheels are often the trade-off for a number of reasons. Getting bigger rims with smaller tires will make the ride harsh but it seems to make the ride height appear more aparent so people often buy expensive wheels notice the difference then compound the ride by adding lowering springs or Coilovers. Effectively making a nice luxuriously riding car into a harsh feeling low rider. Personally I have found a perfect balance. Although I did go with Coilovers because it was a less expensive solution to replacing the OEM shocks with lowering springs, however I immediately noticed the difference in ride quality. When I ride with the stock 18s it's quite bad especially if the streets you drive on are bad. I am currently on 17s with 50 profile tires and the ride is like a dream compared to the 18s. My next investment is a nice set of 17x8 or 9 rims with summer tires. Only drawback is if you have the BBK 17's won't fit, not sure about 18s. The other thing to consider is the cost to replace one tire. If you choose 19 or 20 each tire might run you $200-$300 vs $100-$200 for a 17.

When you say you hear the gears do you mean you hear a whining sound like this https://www.youtube.com/watch?v=6SNm9kiw9Dk

[Scholarjahh]

No pardon me for the mic conception... It runs smooth it's just I can hear when the car goes from first to second n so forth n so on... Now as far as rims go I live in Brooklyn so I'm lookin for something that looks good n can handle bumps without lowering my car . I don't like that

[Ilya]

Can you describe the sound?

[Larz]

I reckon you mean you DON'T hear anything bad, but you are able to hear the transmission working and you didn't hear it before. I wonder if you changed tire brands recently? You may also want to have the fluid level checked or changed if you haven't done so recently.
As for the wheel size (assuming you buy wheels with the required offset) etc ... I am thinking about changing out my wheels from the OEM 18 X 8 to a 19 X 8.5 size. I think 20s 'look' too large on our cars, but that is a matter of personal preference.
However, if you go to 20s, you may need to use a smaller sidewall (say 245/40 or 245/30) and that will give you a more harsh ride and place you at higher risk over the famous NY craters in the roadway. With 19 X 8.5s you can go to a wider 255/45 or maybe even 265/45 and still have the same sidewall size without increasing risk from potholes or changing the OEM suspension.
Perhaps others who have had more experience with wheel sizes can chime in with more advise.

[szh]

I own a 2007 m35x just want to know what's the best size rims to upgrade.

Whatever you eventually settle on, please make sure to have identical wheels and tires on all four corners.

This is essential on the X models ... avoids early wear and tear (and failure) of the AWD system.

Z

[TDot]

The entire suspension system on this car is so bad to me you won't notice a difference if you go to 19 or 20. I say this coming from other luxury cars. I went with 19 first and stayed with them for 1 year and didn't notice ANY difference. Now I'm on 20s with 19" profile tire, so I ride exactly as I would on the 19s. You MAY notice a difference going from 18-20 if you simply drive without a care, but I now try to avoid potholes like the plague so I don't see the harshness in driving. One thing to keep in mind, the bigger the rim and lower the tire profile, the easier your rim will bend when you hit something, especially with aftermarket rims.