i want to run 5x100 15x7 +40mm offset rota slipstreams with a set of 245/50/15 bfg drag radials up front. Dropped on S-Tech's.

any rubbing?


not for everyday of course, but for track days.

 

I do not see a listing on BFGs site for a 245/50-15. The only thing I see that would fit for sure is a 225/50-15 and that would put you a good inch shorter than stock. If your just going to be using these for track use like you say I would look into the 235/60-15. This is a tall tire at 26" but it should help with the overall gearing on the track. I am not sure they will fit with S-techs. I know they will fit with coilovers with the right offset. I was going to use this size for track use before I decided to get a BBK.

 

As the poster above stated, BFG doesn't currently make 245/50-15 for either of their drag radial lines. I think the 225/50-15 would work fine, as the OD would be just .76" shorter than stock (23.858 vs 24.618, respectively), and would effectively lower your gearing for potentially better performance. The alternative 235/60-15 is not only much taller than stock, but also much heavier at 26 pounds, compared to the 225/50-15 drag radial which is close to the stock tire weight, at 22 pounds. If you're not running an LSD but have more power than stock, sometimes a taller tire can be an advantage, as the contact patch will be longer, but that might be offset by the weight & gearing. If either or both will fit (not certain, but I think they would, you might want to call TheTireRack and ask), it's difficult to say which would be best for you without having more info about your mods & goals.

And just so no one gets the wrong idea, no, it's not a good idea to run low-profile 235 width tires on the stock wheels or any 7" rim. The reason it would be ok in this scenario, is due to the 50 series or greater aspect ratio.

 

i'd just like to be able to get the car into the mid 14's with my setup. right now i can pull low 15's (and i know the car is capable of upper 14's if i launch correctly) and with some stickier tires, i'm sure that mid 14's are attainable.

I've got I/H/E/Pullies/ETD. no LSD.

 

Gave this more thought, and considered what I'd do in the same scenario. Of the two possible choices discussed, 225/50 vs 235/60, I'd personally go with the former, 225/50-15. You might also want to experiment with launching in 2nd instead of first, as doing so might produce better times with that size & type of tire on the car.

 

If i can hold traction with a moderate slip of the clutch on 18's and comming out around 2500 rpms, what kinda of traction will I see with the drag radial setup? What i'm really looking for is about how high of an rpm should i slip out at? What kind of tire pressure? I run 22 psi at the track now w/ the 18's, is that about what I want to drop the DR's down to also?

 

bump, im wondering the same thing...

 

2500rpm also happened to be the point Sport Compact Car used when they initially tested their project tC, finding that produced the best times with the 18" package.

It's difficult to guess how much that'll change and in what ways, by going to drag radials with the 15" wheel. You'll have no choice but to experiment launching at different rpms in order to determine what produces the best 60ft times for your specific setup.

As for pressure, yes, once you're at the track you'll want to lower the pressure in the drag radials. They like more pressure than pure slicks, but again this is something you'll need to experiment with to see what pressure produces the best results. This is often in the 14-16psi range for the BFGs on many FWD cars, but can vary quite a bit.

Sorry, but there are no hard & fast, exact answers to these questions. Once you find what works best for your setup, post the results so that those in the community with similar setups might have a decent starting point.