[Luie]

About time to put a set of tires on the 2014 320i. It has the factory 17 wheels painted black right now sporting the 225-50R17. Is there a safe "One Up" size tire I can get? Id like just for the look get a slighty wider rear tire maybe. Hell even wider all the way around would be fine. 225-50 to a 255-45 maybe?

Thanks for any input,

Luis

[alohasurftoad]

you have style 393 with are 17x7.5. technically, 255/45/17 is too wide for a 7.5". could a tire shop squeeze the bead and force it on? probably, however your car will have sloppier turn in and feel wallowy due to the shoulder rolling under during weight transfers.

the widest on 7.5" is 245/45/17. at 25.7", it is a little shorter and may still feel slightly sloppy and wallowy. it will look better if you are slightly lowered.

235/50/17 is 26.3" and fits better on 7.5". being slightly taller, it will fill your fenderwell gap if you aren't lowered, however it's taller sidewalls may give a slightly beefier appearance. since your wheels are black it may not matter as much since black wheels don't have much definition, especially from afar. personally it's the size i'd use(for your situation) however there are less choices available in this size.

[Luie]

To me the tires I have on it now looks too narrow for wheel width now. Look at the front wheels/tires in my photo. Maybe just me though..

[alohasurftoad]

generally, with high performance low profile tires, it's optimum performance occurs when the actual tread width is the same or up to 0.5" narrower than the wheel width.

on tirerack, MPS4S 225/50/17, rim width range 7"-8.5", tread width is 7.5" so it's at the optimum size for the 7.5" wheel width. personally, if going wider i'd run a tire width that fits no less than the minimum wheel width. when you bulge the sidewall, the contact patch and sidewall performance is not optimal, even if you have more overall total width.

you may or may not be able to feel or realize if there's a difference in performance but that is what is occuring.

[Machinebuilder]

I have 235/50/17 tires on my BMW 440 with 17" wheels for my snow tires. The size works and looks great in my opinion. Selection is limited but if you look around you will find there are some available.

[Blueeyesredpanda]

255 on a 320i lol

[Luie]

Originally Posted by Machinebuilder

I have 235/50/17 tires on my BMW 440 with 17" wheels for my snow tires. The size works and looks great in my opinion. Selection is limited but if you look around you will find there are some available.

Thanks man. Appreciate the input...

[chowser51]

these are 235/50/17 square on non-lowered xdrive 430

[Luie]

Originally Posted by Blueeyesredpanda

255 on a 320i lol

What's so funny...

[johnung]

Originally Posted by alohasurftoad

generally, with high performance low profile tires, it's optimum performance occurs when the actual tread width is the same or up to 0.5" narrower than the wheel width.

on tirerack, MPS4S 225/50/17, rim width range 7"-8.5", tread width is 7.5" so it's at the optimum size for the 7.5" wheel width. personally, if going wider i'd run a tire width that fits no less than the minimum wheel width. when you bulge the sidewall, the contact patch and sidewall performance is not optimal, even if you have more overall total width.

you may or may not be able to feel or realize if there's a difference in performance but that is what is occuring.

It's interesting that you say that about tread width vs wheel width. That best handling would be if tread width is the same to 1/2" less than wheel width.

I've got BMW 400M 8.0"x 18" ET34 square setup. I've got the Michelin Pilot Sport 4S 245/40-18 which is supposed to be the best handling size. But checking, the tread width is 8.4" which is more than the 8.0" wide wheel.

The alternative would have been the 245/45-18 which has a taller sidewall for more comfort. But checking, the tire tread width is only 8.1". So with the rule of thumb, the taller 245/45 should actually handle better.

My 245/40-18 MPS4S will need to be replaced sometime next year. It would be nice to gain a little more comfort without sacrificing handling.

By the rule of thumb, the 245/45-18 with an almost identical tread width and wheel width should actually handle better, in addition to the extra comfort that the additional sidewall height should provide.

I'm curious to hear your thoughts on this. It will help me to decide whether to go with 245/40-18 again, or try the 245/45-18?

[alohasurftoad]

Originally Posted by johnung

It's interesting that you say that about tread width vs wheel width. That best handling would be if tread width is the same to 1/2" less than wheel width.

I've got BMW 400M 8.0"x 18" ET34 square setup. I've got the Michelin Pilot Sport 4S 245/40-18 which is supposed to be the best handling size. But checking, the tread width is 8.4" which is more than the 8.0" wide wheel.

The alternative would have been the 245/45-18 which has a taller sidewall for more comfort. But checking, the tire tread width is only 8.1". So with the rule of thumb, the taller 245/45 should actually handle better.

My 245/40-18 MPS4S will need to be replaced sometime next year. It would be nice to gain a little more comfort without sacrificing handling.

By the rule of thumb, the 245/45-18 with an almost identical tread width and wheel width should actually handle better, in addition to the extra comfort that the additional sidewall height should provide.

I'm curious to hear your thoughts on this. It will help me to decide whether to go with 245/40-18 again, or try the 245/45-18?

the treadwidth-tirewidth thing is for the tires optimal performance on a given wheel width, not necessarily the best overall handling, as there maybe other factors. when going oversize width on a narrow rim, the tire shoulder tends to roll under during loading and the sidewall stiffness is lessened creating more slop. if you stretch the tire it's also not good since the sidewall flex is diminished with more unpredictable breakaway. i probably should have just said to stay within the rim width range recommended for the tire size, there's a reason for it.

for your next tire i would do 245/40/18 again or 235/45/18 i.e. https://f30.bimmerpost.com/forums/sh...F45%2F18+dummy 245/45/18 will make your gearing at the pavement taller and it's taller sidewall will have more slop. but if you do choose 245/45/18 definitely give us a review.

here is an article i referenced for information...https://motoiq.chttps://f30.bimmerpo...haracteristics.

[johnung]

Originally Posted by alohasurftoad

the treadwidth-tirewidth thing is for the tires optimal performance on a given wheel width, not necessarily the best overall handling, as there maybe other factors. when going oversize width on a narrow rim, the tire shoulder tends to roll under during loading and the sidewall stiffness is lessened creating more slop. if you stretch the tire it's also not good since the sidewall flex is diminished with more unpredictable breakaway. i probably should have just said to stay within the rim width range recommended for the tire size, there's a reason for it.

for your next tire i would do 245/40/18 again or 235/45/18 i.e. https://f30.bimmerpost.com/forums/sh...F45%2F18+dummy 245/45/18 will make your gearing at the pavement taller and it's taller sidewall will have more slop. but if you do choose 245/45/18 definitely give us a review.

here is an article i referenced for information...https://motoiq.chttps://f30.bimmerpo...haracteristics.

Thanks, man! You are the voice of reason as usual. I'll stick with the MPS4S in 245/40-18 again. Incredible summer tires.

I'm not one to fixate on the looks of tire/fender gap. I really don't care about the look. But my front end actually feels a little high to me when I drive. I've already got Eibach springs with Koni Special Active Struts/Shocks. So the drop is front 0.8" and rear 0.6" on a 2015 335i xDrive. I also have H&R sway bars, a strut brace and monoball thrust arms.

I'm researching a bit to see if my KoniSA's can handle a little more front drop (maybe 0.4" to a 1.2" total front drop) and if I can find springs with characteristics of the Eibach front springs but that are a little lower. Just seeing what else that I can tweak for a little improvement.

[gcbcbc]

Originally Posted by Luie

What's so funny...

Probably because you wouldn't need that wide of a tire for the 320. I say do whatever you like. Maybe it'll help with braking distance?
It'll definitely look cooler