I'm trying to decide whether to run 205/50/15 BFG drag radials, or the 225/50/15 size for my setup (stock SOHC, SC50, Z6 tranny w/LSD).

I'll be making around 220-230whp on the Z6 tranny and stock Y8 motor, and I'm wondering which tire size would be better for my tranny/low-WHP setup?

RyanCivic2000 posted a thread called "Wheel/Tire combo for 300whp civic" and got some interesting responses, and he concluded that even though the 225/50/15 size puts down a larger contact patch, there will be issues with gearing (entering 5th maybe?):

https://honda-tech.com/zerothread?id=1350946

Thoughts? Should I run the 205/50/15 or 225/50/15 BFG's? I will be running them on 15x6.5" Rota Grids.

EDIT: For the record, I know nothing about gearing vs. tire size (if you couldn't tell).

 

The launch is the slowest part of the race. If the 225s get you out of the hole quicker (less wheelspin and a higher launch RPM allowable) then they are the better choice Gearing is less of a factor in that regard!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by raene &raquo;</TD></TR><TR><TD CLASS="quote">The launch is the slowest part of the race. If the 225s get you out of the hole quicker (less wheelspin and a higher launch RPM allowable) then they are the better choice Gearing is less of a factor in that regard!</TD></TR></TABLE>

But would I have to shift to 5th gear with the taller 225's? Should that be a concern for me, or am I too slow?

 

The 225 is not the height of the tire. This is the contact patch width of the tire. The 50 is the actual height of the tire. The larger the number the taller it will be. The 205/50/15 or 205/55/15 will be a good start to practice on and see where it will put you. Don't go too big thinking it will net a ton more traction because it won't, especially with drag radials. It will just make turning a problem due to scraping, etc.

 

You might have to shift to 5th with SHORTER tires, not taller... if you got bigger tires then that's less shifting and taller gears.

I don't know if I agree with msmotorsports provided the rims you mount the tires on are wide enough... more contact patch means more traction. I had that situation with my 22" slicks, had them on 6.5" rims and could barely get high 1.9s, got wider rims and had 1.84's hardly even trying.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by raene &raquo;</TD></TR><TR><TD CLASS="quote">You might have to shift to 5th with SHORTER tires, not taller </TD></TR></TABLE>

Exactly. I believe you have things mixed up boostincoupe.

IMO, the 225/50 will be your best choice. It'll be the easiest of the 2 sizes to control wheelspin with (SOHC's regardless of the WHP number make great WTQ. and that's what spins tires) and if you ever decide to make more power you'll have more room (hence gearing relation) for more MPH in 4th gear to increase. With 230whp though you'll only be trapping about 110mph.

Phil

EDIT: I just did the calculation for you. See below.

225/50 w/ a 7K rev limit will go 128mph in 4th w/ the Z6 trans.
205/50 w/ a 7K rev limit will go 122mph in 4th w/ the Z6 trans.

 

Go 225's. You shouldn't have an issue with clearance and even 230whp will spin em.