03-17-2021, 02:27 PM | #1 |
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Recommended Tires / Slicks
Good day all,
I am looking to get racing tires for BMW F30 330e Msport. It originally came with 400m rims - 8,5x18 255/40R18 ET 47 Currently I have 437m rims - 10x19 275/35R19 ET 40 I was looking at Hoosiers 28-10/18 but unsure if that will fit as it is 28" diameter while stock is 26". Anyone in here used slicks on a f30? My car also has the standard small brakes so I believe 17" or even 16" should fit. I tried R888R on the 18" but could not hold. I am also rolling off line gently going on throttle as if I go full throttle I will only burn out as my car is hybrid and the electric motor as well as small turbo provides 440wft-lbs of instant torque. Also my local track is appears to be not the best prepped, I am getting 2.3+s 60ft time on track while on streets I'm getting 1.94s with the R888R. Thank you. Regards, Shane |
05-18-2021, 01:36 PM | #2 | |
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I don't know if you've figured it out yet but tires are not going to be your solution here. You need a limited slip differential upgrade. It is the only effective way to cure this problem. I have a tuned F30 335i with bolt on's. On map 7 I'm putting down over 500ft-lb to the wheels. When I track or autocross I run into significant issues getting both rear tires to stick when doing hard turns. Last event I lost over 2 seconds on a 68 second lap simply waiting for both tires to have traction. All of the RWD cars that were faster than me have the same thing in common. They all have limited slip differentials. I used to run MPSS 255's at 40PSI which didn't work. Then I went to RE-71's (<200 TW) at 45PSI, though significantly better still didn't come close to solving the problem. So my $0.02. An LSD is the solution you're looking for. Full slicks may help significantly and will certainly help lower lap times. However at some point one of the tiers will break traction and you'll one wheel peel again. |
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05-24-2021, 11:39 PM | #5 |
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R888's are crap. I use RE71R's. 45 hot is above the optimal pressure. I keep it between 32 and 38.
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05-26-2021, 10:42 AM | #7 |
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05-27-2021, 02:15 PM | #8 |
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I initially thought so also. However, this seems to be the most sticky with those pressures. I gain almost 1 second on ~68 second laps going from 38/42PSI to 43/46PSI. ~38/40PSI there is too much sidewall flex.
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05-27-2021, 03:56 PM | #9 |
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Agreed. I was at LRP yesterday and it was a hot ass 90+ day. I had a two hour ride up so I couldn't get the tires cooled down enough to accurately set my base pressure. Went out on the first session and I was really struggling for traction, fighting the rear end way more than usual. See the clip. I rolled back in and it was at 41PSI in the rear with the center tread almost 20 degrees over the edges (classic sign of over inflation). Once I set my typical hot pressures of 36/38 and the car was locked down the rest of the day. Cold it's about 28-29F and 31-32R.
Obviously setups being different there is no "correct" pressure and everyone has different tastes, but that's what I have stuck close to since moving to 200tw.
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05-28-2021, 12:22 PM | #10 | ||
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GPlus intercooler and CP. Stage 1. CG precision dp. Staggered 19?s. 275/35/19, 245/40/19 ps4s. |
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05-28-2021, 05:02 PM | #11 | |
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2015 335i 6sp manual with MPK and sport pack
GPlus intercooler and CP. Stage 1. CG precision dp. Staggered 19?s. 275/35/19, 245/40/19 ps4s. |
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05-30-2021, 06:44 AM | #12 | |
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So many variables to be considered when talking about pressures. The gain may also be from your improvement and better understanding of the course layout so it is very possible that there was still time to be saved out there. Pyrometer might be a good investment to tell you if you are in fact maximizing your contact patch and give you some indication on pressures. When I was running an RE71 in 245 40 18, i was in the 34-36 psi area but I had a bunch of suspension goodies so that affects things. |
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06-07-2021, 10:49 AM | #13 | |
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The most recent challenge I completed 6 runs then my car sat for 3 hours. At the end of the 3 hours I aired back up to 38/40 psi and was about a full second slower than my previous best lap. After that first challenge lap my pressures went up to 43/46 psi and I gained my second back. In the high 30's I can feel the sidewall flexing which seems to go away in the mid 40's. I'm no expert by any means but that was my most recent experience. |
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06-07-2021, 10:51 AM | #14 |
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06-09-2021, 11:21 AM | #15 | |
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I have a friend who used run a stock 240 and he was running 255/265 re71s...he ran 44 psi and he was quickest that way so there is no one formula that is always correct. if high pressures are working for you then keep doing it. |
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