[G30M]

so despite the M340i being the most neutral car i've ever had (first BMW), it still has very mild understeer.

(if you watch Mischa Charoudin's manual M4 video he also says the RWD G82 M4 has mild understeer - and that wheel alignment tweaks will reduce that)

has anyone read about which wheel alignment tweaks i can do to reduce the understeer?

currently have staggered 225 front 255 rear - the BMW wheel offset of the 225 compensates for the narrower tyre and brings it out wider to match the rear.

i'm going to 255 square, and because i'll be using wheels of the same offset, most of the 3cm extra width of the front tire is going to go inside the car, making only a 2mm difference each side in front track width (4mm total extra width for both sides)

not sure how this will change the understeer

thanks for any tips

[Knifeedge2k1]

Originally Posted by G80M4

so despite the M340i being the most neutral car i've ever had (first BMW), it still has very mild understeer.

(if you watch Mischa Charoudin's manual M4 video he also says the RWD G82 M4 has mild understeer - and that wheel alignment tweaks will reduce that)

has anyone read about which wheel alignment tweaks i can do to reduce the understeer?

currently have staggered 225 front 255 rear - the BMW wheel offset of the 225 compensates for the narrower tyre and brings it out wider to match the rear.

i'm going to 255 square, and because i'll be using wheels of the same offset, most of the 3cm extra width of the front tire is going to go inside the car, making only a 2mm difference each side in front track width (4mm total extra width for both sides)

not sure how this will change the understeer

thanks for any tips

I can't speak to whether you bringing the center of the contact patch inboard will do on its own but having wider front tyres will naturally reduce understeer by itself.

Settings which reduce understeer (when compared to a relatively stock setup)

-more negative(less positive) front wheel camber
-more positive(less negative) rear camber
-more front caster
-more rear toe out (generally you don't want any toe out in the rear, I should have said less rear toe in)
-more front toe out
-more rear roll stiffness (stiffer sways, higher rear spring rate, stiffer rear compression damping)
-less front roll stiffness (softer sways, softer springs, less compression damping)

Getting stiffer rear sways is basically a no brainer to start. You can go aftermarket or you can just get OEM sways from the most hardcore version of your platform.

[PLF69]

Originally Posted by G80M4

so despite the M340i being the most neutral car i've ever had (first BMW), it still has very mild understeer.

(if you watch Mischa Charoudin's manual M4 video he also says the RWD G82 M4 has mild understeer - and that wheel alignment tweaks will reduce that)

has anyone read about which wheel alignment tweaks i can do to reduce the understeer?

currently have staggered 225 front 255 rear - the BMW wheel offset of the 225 compensates for the narrower tyre and brings it out wider to match the rear.

i'm going to 255 square, and because i'll be using wheels of the same offset, most of the 3cm extra width of the front tire is going to go inside the car, making only a 2mm difference each side in front track width (4mm total extra width for both sides)

not sure how this will change the understeer

thanks for any tips

Going 255 square (my track setup) will mostly eliminate the under-steer you talk about.

Another option would be to replace the front 225 tires for 245 on the same oem from wheels, costs less and you will gain almost the same effect, which I think is well enough.

As for alignment, there is not much to do without a way to adjust camber, you can go to a 0 toe setting which will make the front more responsive. Adding camber (by either camber plates or naturally when lowering) will improve the contact patch when cornering witch should tame under-steer.

[Burrcold]

Keep in mind if you change alignment settings to help reduce understeer, daily drivability usually ends up suffering (twitchier on center feel and more tramlining).