[TomFord514]

Hello, I’m new to this and need help with getting the correct tire size. I’m downsizing from 20” to 18” due to bad road conditions. I have a 2018 330i Xdrive with Blue m sport brakes and was looking to go square set up for more comfortable drive. Please let me know if the following will fit ok without any issues with rubbing etc. Thank you all so much for your help!

Mags: 18” 8.5 width and 40 offset
Tires: Michelin ps4s 235/45/18

[alohasurftoad]

Originally Posted by TomFord514

I have a 2018 330i Xdrive with Blue m sport brakes and was looking to go square set up for more comfortable drive. Please let me know if the following will fit ok without any issues with rubbing etc. Thank you all so much for your help!

Mags: 18” 8.5 width and 40 offset
Tires: Michelin ps4s 235/45/18

the above setup will fit without any issues. it will appear slightly more tucked than most prefer.

[TomFord514]

Thank you for your input.
Do you recommend spacers? Is it safe?

[alohasurftoad]

Originally Posted by TomFord514

Thank you for your input.
Do you recommend spacers? Is it safe?

ideally, wheels with an offset that doesn't require spacers is more desirable because spacers require longer lug bolts. however if you desire a less tucked appearance, you'll need to get some.

i suggest you put the wheels on 1st. then come back here to determine spacer thickness to use.

[TomFord514]

Yeah that makes sense. I’m not super picky about look but I don’t want it to look skimpy obviously. My goal here is to achieve a higher profile due to many pot holes. I was running a staggered set up before and would blow at least a tire a month..

225/35R20
255/30R20

So with the new set up if you think I should add a spacer (size you recommend for front and back) to look nicer, then I will guarantee go with your input as you are a lot more knowledgeable than I am.

[alohasurftoad]

Originally Posted by TomFord514

So with the new set up if you think I should add a spacer (size you recommend for front and back) to look nicer, then I will guarantee go with your input as you are a lot more knowledgeable than I am.

https://f30.bimmerpost.com/forums/sh...35&postcount=6

solidjake has the same specs 235/45/18 on 18x8.5, except with ET35. you would need a 5mm to match the appearance solidjake has. the front and rear spacer sizes need not be identical if you are really picky about the appearance. as you increase spacer thickness it reduces the stock hub lip, which can be remedied with hub extenders for an additional cost. spacers over 12mm will have built-in hub extenders but at this point you may as well have ordered lower offset wheels.

put the wheels on 1st, post some pics and determine the spacer size later

[TomFord514]

Great thanks for the info! Once winter is over and everything installed I’ll upload some pics and hopefully you can get to see them and give your input

[TomFord514]

By the way, what psi do you reccomend? On my door is 32 front and 36 rear but that’s for stock tires that came with the car.

225/40/19
255/35/19

Would it still be the same? Or is a square set up different? And now gonna be 18”?

[alohasurftoad]

Originally Posted by TomFord514

By the way, what psi do you reccomend? On my door is 32 front and 36 rear but that’s for stock tires that came with the car.

225/40/19
255/35/19

Would it still be the same? Or is a square set up different? And now gonna be 18”?

i believe cars that came with square OEM setup have square tire pressures and staggered setups have different front and rear pressures based on weight over axle, tire size(s), tire type(runflat/goflat/performance/touring) and maybe other factors i am unaware of.

you can try the staggered door card psi on the square setup and see how it feels. personally, i would run square psi on square fitment and if necessary, adjust each axle as desired or if peculiar wear is noticed. if goflats, i'd probably start with 35 psi and go from there, 32 if runflat. just remain sensible about it.

[TomFord514]

Ok makes sense. Just ordered the michelin pilot sport 4s 235/35/18. I’ll try 35psi all around and see what that feels like. Also, since you seem to know a lot about cars lol is it normal for only one exhaust to seem like it’s working? I modified my stock exhaust and bought a 335i to have the single dual outlet on both sides for aesthetics and noticed that smoke only comes out from the right pipe. Does this have to do anything regarding being valved? Or do you think think there is something wrong with the exhaust?

[alohasurftoad]

Originally Posted by TomFord514

Just ordered the michelin pilot sport 4s 235/35/18.

Also, since you seem to know a lot about cars lol is it normal for only one exhaust to seem like it’s working? I modified my stock exhaust and bought a 335i to have the single dual outlet on both sides for aesthetics and noticed that smoke only comes out from the right pipe. Does this have to do anything regarding being valved? Or do you think think there is something wrong with the exhaust?

why 235/35/18? that diameter is 24.5". OEM diameter is 26". your fenderwell gaps will be immense and your car will be 19mm lower. you will also accrue 6.1% more mileage on your odometer than actual and your speedo will be off by the same as well.

regarding the exhaust, it is normal operation.
https://f30.bimmerpost.com/forums/sh...ious%20reasons.

[TomFord514]

My apologies it was a typo! I meant to write 45 profile!

[TomFord514]

Any suggestions on a high flow midpipe? Was wondering if the 340i dinan would bolt right up to my car since I changed the exhaust.

[GamaM440]

guys how Strick you are following the 1% criteria on x drive straggled tire set up , please have a look as i am just above 1% like 1.03 and 1.04%

[alohasurftoad]

Originally Posted by TomFord514

Any suggestions on a high flow midpipe? Was wondering if the 340i dinan would bolt right up to my car since I changed the exhaust.

imo the OEM mid-pipe is more than adequate for flow. however if you really want an aftermarket mid-pipe, AWE is what i'd get. Dinan is not the same as they were 15 years ago. While they're still decent imo they're stuff is overpriced and there's just better stuff and brands to consider.

if you want more power from the exhaust, a catted downpipe is pretty much the only way to go. Active Autowerke is what i'd get, but it's not cheap.

[TomFord514]

Thanks for the heads up. I was looking into the AWE midpipe as well. Would I have any issues with install? Or it’s pretty much plug and play. I’m actually running a VRSF catless downpipe! It’s more for sound rather than performance.

[alohasurftoad]

Originally Posted by TomFord514

Thanks for the heads up. I was looking into the AWE midpipe as well. Would I have any issues with install? Or it’s pretty much plug and play. I’m actually running a VRSF catless downpipe! It’s more for sound rather than performance.

Since you can run any one component adjacent to oem, I would think it is plug and play, however it's better to contact the manufacturer to be sure. You can also ask in our b48/n20 sub-forum as well for multiple response.