Track Tire Sizes

[jewels]

So I am asking for an opinion here on which tire size to use on my new 19" wheels for the track on my M4
Going with 305/30R-19 rears 26.3" diameter..I am set there.

Fronts I am trying to figure out if I should go with 265/35-19 26.4" Dia. or
275/30-19 25.6 dia...or 275/35-19 26.6 dia.

Was trying to leave the balance in diameters as close to the stock diameters as possible in difference front to back //originals are 26.6 rear-26.1 front.

I am leaving the suspension stock and the car is a DD with the stock wheels.

My experience level is Instructor (red) for over 10years, but none of my track time has been in BMW's till now.

I know opinion will vary but I would appreciate any & all comments.
Thanks

[Gearhead999s]

Originally Posted by jewels

So I am asking for an opinion here on which tire size to use on my new 19" wheels for the track on my M4
Going with 305/30R-19 rears 26.3" diameter..I am set there.

Fronts I am trying to figure out if I should go with 265/35-19 26.4" Dia. or
275/30-19 25.6 dia...or 275/35-19 26.6 dia.

Was trying to leave the balance in diameters as close to the stock diameters as possible in difference front to back //originals are 26.6 rear-26.1 front.

I am leaving the suspension stock and the car is a DD with the stock wheels.

My experience level is Instructor (red) for over 10years, but none of my track time has been in BMW's till now.

I know opinion will vary but I would appreciate any & all comments.
Thanks

I would go with the 275/30 up front as a 26.6 high tire would be of concern for clearance.I settled on a 275/30 295/30 in 19 to maintain a stock stagger relationship.I had a brake balance issue with the ABS when running a square 275/35 18 on my previous E92 M3 which had a Stoptech 380 BBK on it.

[FTS]

Based on my experience with some of the electronics, particularly with BOSCH and Siemens used on some car (not BMWs), I would try to be as close to stock diameter and RPM differences as possible. 0.3" is probably the tolerance, meaning instead of 0.5-0.6" front to rear diff, may be the programming can tolerate half of that up or down. I certainly am not looking forward to finding out first-hand, so I will keep the 0.6" difference with my setup; probably 265/35 and 295/30, or 295/30 and 305/30 combinations.

[Gearhead999s]

Originally Posted by FTS

Based on my experience with some of the electronics, particularly with BOSCH and Siemens used on some car (not BMWs), I would try to be as close to stock diameter and RPM differences as possible. 0.3" is probably the tolerance, meaning instead of 0.5-0.6" front to rear diff, may be the programming can tolerate half of that up or down. I certainly am not looking forward to finding out first-hand, so I will keep the 0.6" difference with my setup; probably 265/35 and 295/30, or 295/30 and 305/30 combinations.

I was told that 3% is the critical number for diameter.2.26% is the difference from a 275/35 19 to a 255/35 19 which is BMW's recommendation on all 4 wheels for winter tires.2.31% is the height difference on a 275/30 19 295/30 19 which is why I decided to go that way after confirming that I could get an 11" rear wheel.

[jewels]

Originally Posted by Gearhead999s

I was told that 3% is the critical number for diameter.2.26% is the difference from a 275/35 19 to a 255/35 19 which is BMW's recommendation on all 4 wheels for winter tires.2.31% is the height difference on a 275/30 19 295/30 19 which is why I decided to go that way after confirming that I could get an 11" rear wheel.

Any concerns with the factor of the 275/30 19 & 295/30 19 being a lower (shorter tire) than stock...think maybe better handling?? I am wondering the effect of this or am I being too critical over such a small difference??
Your analysis was me rethinking my 305/30-19 choice. I was trying to eliminate the tail happy thing as much as possible with the biggest foot print with in reason.

[Gearhead999s]

Originally Posted by jewels

Any concerns with the factor of the 275/30 19 & 295/30 19 being a lower (shorter tire) than stock...think maybe better handling?? I am wondering the effect of this or am I being too critical over such a small difference??
Your analysis was me rethinking my 305/30-19 choice. I was trying to eliminate the tail happy thing as much as possible with the biggest foot print with in reason.

Not at all.I ruled out running an 18" setup due the fact that I could not find a tire that would allow the stagger that I wanted/needed in sizes that would work.In 19 there were a few choices that would work and my other factor is that I needed tires with a 140+ wear rating for the Ontario 1500 in September.

www.ontario1500.ca

[MaynardZed]

I've been using 265/30 in the fronts for the track with no problems, but 265/35 might look better since it will fill in the stock wheel gap a little better. R888 come in both sizes, I think I'll try the latter next time. I don't think with this suspension/steering we'll notice much difference in responsiveness.

What are the specs of your track wheels?

[Gearhead999s]

Originally Posted by MaynardZed

I've been using 265/30 in the fronts for the track with no problems, but 265/35 might look better since it will fill in the stock wheel gap a little better. R888 come in both sizes, I think I'll try the latter next time. I don't think with this suspension/steering we'll notice much difference in responsiveness.

What are the specs of your track wheels?

I am getting Forgestar F14's 19x10 25P 19x11 33P.

[FTS]

Originally Posted by jewels

Any concerns with the factor of the 275/30 19 & 295/30 19 being a lower (shorter tire) than stock...think maybe better handling?? I am wondering the effect of this or am I being too critical over such a small difference??
Your analysis was me rethinking my 305/30-19 choice. I was trying to eliminate the tail happy thing as much as possible with the biggest foot print with in reason.

I do not know much about that "3%" tolerance you mention, but I think understand your reasoning. What I am concerned about is not the diameter difference between tires for a given corner of the car, but more about diameter differences between front and rear tires compared to stock.

For example, stock tire diameter difference is 0.6" front being lower (26" front and 26.6" rear). I am preferring to stay at between 0.3" to 0.9" difference for track tires. What I would not recommend is choosing tires with front diameter close to same or higher than the rears.

[Gearhead999s]

Originally Posted by FTS

I do not know much about that "3%" tolerance you mention, but I think understand your reasoning. What I am concerned about is not the diameter difference between tires for a given corner of the car, but more about diameter differences between front and rear tires compared to stock.

For example, stock tire diameter difference is 0.6" front being lower (26" front and 26.6" rear). I am preferring to stay at between 0.3" to 0.9" difference for track tires. What I would not recommend is choosing tires with front diameter close to same or higher than the rears.

I do not think my size choice is different enough from stock to cause any issues.My main concern was to try to keep the width & height ratio the same as stock as I feel the car is fairly well balanced but could use more overall grip especially at the rear.I might plan a trip south in March to get a early track day in as our season usually does not start till mid April.

[jewels]

Originally Posted by FTS

I do not know much about that "3%" tolerance you mention, but I think understand your reasoning. What I am concerned about is not the diameter difference between tires for a given corner of the car, but more about diameter differences between front and rear tires compared to stock.

For example, stock tire diameter difference is 0.6" front being lower (26" front and 26.6" rear). I am preferring to stay at between 0.3" to 0.9" difference for track tires. What I would not recommend is choosing tires with front diameter close to same or higher than the rears.

So it looks like my decision after reading all if this (THANK YOU) is
F-275/30-19 25.6 dia. R- 295/30-19 26 dia. or
F- 295/30-19 26 dia. R-305/30-19 26.3 dia.
Any further comment would be appreciated

[Gearhead999s]

Originally Posted by jewels

So it looks like my decision after reading all if this (THANK YOU) is
F-275/30-19 25.6 dia. R- 295/30-19 26 dia. or
F- 295/30-19 26 dia. R-305/30-19 26.3 dia.
Any further comment would be appreciated

I do not think you would get a 295/30 19 in the front as you would need an 11 " rim IMO.

[AMPowerJ]

Originally Posted by Gearhead999s

I am getting Forgestar F14's 19x10 25P 19x11 33P.

Any idea what those weigh?

[Gearhead999s]

Originally Posted by AMPowerJ

Any idea what those weigh?

My wheel guy told me he was surprised at how light they were for 19's and I think he told me around 22 lbs for the 10's.

According to **********s.com,
Forgestar F14 18" weigh:

•18x8.5 ET48 - 17.6 Lbs.


•18x9.5 ET48 - 18.4 Lbs.


•18x10 ET42 - 18.2 Lbs.


•18x12 ET68 - 20.0 Lbs.


Click here to enlarge

18x8.5 Forgestar CF5 wheel weighs 19.95 lbs", so is considderably heavier then the F14

[MaynardZed]

Originally Posted by jewels

So it looks like my decision after reading all if this (THANK YOU) is
F-275/30-19 25.6 dia. R- 295/30-19 26 dia. or
F- 295/30-19 26 dia. R-305/30-19 26.3 dia.
Any further comment would be appreciated

Well at least you came to a definite decision.

I'd go with option 1. 295 too big for front, but is fine for the rear. The rear stepping out not as scary as I had feared with this car and I run all DSC off with Dinan tune. Just be judicious with throttle input exiting turns especially in 2nd gear.

[jewels]

Originally Posted by MaynardZed

Well at least you came to a definite decision.

I'd go with option 1. 295 too big for front, but is fine for the rear. The rear stepping out not as scary as I had feared with this car and I run all DSC off with Dinan tune. Just be judicious with throttle input exiting turns especially in 2nd gear.

I agree with your analogy...going with option 1.

My race car was a aircooled 911..always watching for "step out"
Most of my track time now is @ Watkins Glen..no 2nd gear turns

Thanks everyone for the insight.

[CanAutM3]

Has anyone considered the NT01 in 275/35R18 and 305/35R18 sizes? According to the Nitto site, the NT01 rolling diameters (25.55"/26.42") would be very close to the stock 19" (26.0"/26.6").

[jewels]

Originally Posted by CanAutM3

Has anyone considered the NT01 in 275/35R18 and 305/35R18 sizes? According to the Nitto site, the NT01 rolling diameters (25.55"/26.42") would be very close to the stock 19" (25.5"/26.6").

Those tire sizes do not exist in the Yok. AD08R's that I use.
I am sure others would, should consider those sizes if they want NT01 and are thinking of running 18" tires.
Thanks for the input

[w00tw00t]

Why go with 19s? I recommend 18. I have 275/35/18 BFG Rival on 18x10ET33 APEX EC7 Rims Square with 15mm spacers front and 5mm rear on KW CS supension. This is my street summer setup. For track I plan on either Hoosier R6 or BFG R1 ... same size..

[Gearhead999s]

Originally Posted by jewels

Those tire sizes do not exist in the Yok. AD08R's that I use.
I am sure others would, should consider those sizes if they want NT01 and are thinking of running 18" tires.
Thanks for the input

How do you like the AD008R's?

[FTS]

Originally Posted by CanAutM3

Has anyone considered the NT01 in 275/35R18 and 305/35R18 sizes? According to the Nitto site, the NT01 rolling diameters (25.55"/26.42") would be very close to the stock 19" (25.5"/26.6").

I seriously wish NT01s were available in 19, truly great tire for DE and Autox IMHO. Although you may want to double check the rolling diameter information; looking at the Tire Rack site, fronts are shown as 26" and rears 26.6" in 19s. I also measured them as they sit on my car, they are 25.5" and 26.1" with really cold pressures (probably around 30-31 psi).

[jewels]

Originally Posted by Gearhead999s

How do you like the AD008R's?

I have yet to find a track (to the track) tire I like better.

Yes when I was doing all out racing Hoosier was my choice, but for track DE AD008R's are my game

I did settle on 305/30-19 R // 275/30-19 F
Original circumference for fronts were 81.77" ///new size 80.10" about 2% less
Rears same comparison originals 83.50"///new size 82.32" about 1 1/2% less
Rear contact patch goes from 10.83" to 12.01"////Front contact patch goes from 10.04" to 10.83"
I do know there is a debate out there as to having a very slightly shorter tire is not as beneficial as a larger one, but the shorter side wall and larger contact patch is my preferred mixture.