BFG R1 tire story

Matt McGrain · **Posted:** Thu Oct 11, 2007 9:58 pm

Aaron Buckley wrote:

Matt McGrain wrote:

Not to go off on too much of a tangent at this point, but is it all that common for Hoosiers to cord that quick? Speaking from experience on a camber-challenged ITR, my A4's lasted about thirty-five runs or so. I got them flipped the event before they corded and was pretty surpised at the lack of longevity. This really makes the old cost-per-run consideration depressing; and I'm only running 15's. :cry:

I've had my V710's almost two seasons and they are yet to die in contrast. I haven't really had that much experience racing on R-comps but I would say that the Kumho have the same level of grip as the pricier Hoosiers when the A4's were in production.

To end on a good note, perhaps this weekend will do the trick (kill the 710's giving me an excuse to buy new ones and keep the R) considering how many runs we'll probably end up with based on the lower than normal entry.

You need -2 degrees of camber or more up front to get Hoosiers to really last. Kumhos in comparison will run for 100+ runs on a camber challenged car... and that is if you can cord them. Most will heat cycle out by about 80 runs or so and turn into junk, but by that point, I feel the tire was worth it.

Likely Matt your tires are heat cycled out and you'd be amazed at how much better a new set would be. One thing I can say for the Hoosiers are that they are fast right to the cord, but so would the Kumho if they lasted for so little runs

That being said, at Nationals '07, about 90% of the winners were on Hoosiers, as compared to about an even split in '06. - AB

Interesting. Maybe I call chalk it up to experience on R-comps. The Hoosiers were the first set I used and the Kumho's will be the second so it may just be attributed primarily to seat time with stickies (scratches chin in deep thought).

I'm with Mike though, unless I'm going to Topeka, I'll sacrifice a little bit of performance/stickiness for value.

Hats off to the folks that represented THSCC in Kansas, btw. :beerbuds:

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Aaron Buckley wrote:

Kumhos in comparison will run for 100+ runs on a camber challenged car... and that is if you can cord them. Most will heat cycle out by about 80 runs or so and turn into junk, but by that point, I feel the tire was worth it.

Data point -- Corded one V710 in the center of the tread in 47 runs. For 42 of those runs it was on the front of my BS M3 -- swapped it to the rear for 5 runs when it corded (delaminated) with wear grooves showing. Tires are 16 months old.

Maybe I'm getting them too hot or something. In any case, I'm done with V710s for now.

Aaron Buckley · **Posted:** Fri Oct 12, 2007 7:33 am

MikeWhitney wrote:

Data point -- Corded one V710 in the center of the tread in 47 runs. For 42 of those runs it was on the front of my BS M3 -- swapped it to the rear for 5 runs when it corded (delaminated) with wear grooves showing. Tires are 16 months old.

Maybe I'm getting them too hot or something. In any case, I'm done with V710s for now.

Do you spray the tires between runs? We have found that it's almost necessary, except when the ambient temperature is less than 60 degrees. With a single driver, it's not as bad, but still should be monitored. I can understand wanting to ditch them though. - AB

Chuck Branscomb · **Posted:** Tue Oct 16, 2007 6:13 pm

Closing the book on this story for now with this final installment. The 245/40-18 R1s worked great this past weekend at Danville. We ended up settling on a 5psi pressure stagger, lower in rear, and the car was working pretty good. I ended up PAX'ing 3rd which is the closest I've ever been to Jim and David, and if I could have actually not over-driven those cross-runway transitions repeatedly, I could have closed the gap a bit more. On my last run I almost did them right (best of the day) and then barely clipped a cone at the final gate, tripping the lights at a 40.483. Hence the best time clean was 40.776 raw. I think it might be time to at least get a set of Konis for this car -- it still has the stock shocks, and I think I can get some additional performance from adjustable Konis, even SAs.

Jackie PAX'd 15th with a 42.334 raw which she wasn't too happy with; however, being only ~1.6 seconds back from my time is about the best she's driven so far. I think she's doing well learning how to horse 3400 lbs around an autox course.

Tire wear after 22 runs (both of us for both days) was nil. Outside edge wear up front is where most occurs (and where A6s cord after 25 runs or so on this car), and it was not bad at all. These R1s are really the ticket for heavy camber challenged cars at the club autocross level...at least for me. I'm not interested in buying A6s for $274 each, three or more times per year.

A number of people were asking me about the tires this weekend, so I'll recap this thread with a couple of comments:

The 245 R1 is wide as I mentioned up above. It is close to 260mm wide in section width. Hence, be prepared if you order R1s for them to come wide, perhaps even much wider than you expect.
They wear very well -- much, MUCH better than a Hoosier.
They work great on this heavy 330i (empty car weighs about 3370 lbs then add my 200 lbs), and they really do not need spraying. I can't say how a 245 section R1 would work on a much lighter weight car though.
They communicate well through the wheel and seat, at least in the 330i which has outstanding steering. Where the A6 felt dead, the R1 feels alive and ready through the wheel. You know what the contact patch is doing, and the response over the top of the tractive force curve is not to dramatically lose grip. It doesn't trail off like a street tire, far from it, but it doesn't drop off a cliff like the A6 either. In addition, it makes just a bit of squeaking when you are asking too much from it.

I'll end with a pic of Jackie entering the first sweeper carrying the RF tire in the air. I think we've got enough front roll stiffness and the R1 seems to be sticking pretty well. :wink:

JamesFeinberg · **Posted:** Tue Oct 16, 2007 7:07 pm

Nice driving Chuck! Jackie too. You guys are really getting that BMW dialed in.

From the picture, it looks like Jackie is nearly up on 2 wheels. Do you notice much wheel spin from lifting the inside rear that much? I may have missed it but do you have a stock front sway bar?

Jim

Chuck Branscomb · **Posted:** Wed Oct 17, 2007 7:25 am

Jim,

Inside rear tire spinning is what limits this car significantly. You have to manage that with the throttle delicately, especially if there are any 1st gear sections, turn-arounds, etc. It does have a Turner (H&R) front bar, 27mm up from 24mm, that we added at the beginning of this season. That made a huge difference in front tire wear (better) and made the car faster. It also reduced some of that inside rear tire spin business. If this car had a limited slip, it would still be in B-stock.

When I drove that first sweeper, from the apex all the way through almost to the next element, I was spinning the inside rear tire and having to manage it. Same thing but to a greater extent on the turn-around when I tried it in 1st gear at Aaron's suggestion. I ended up using 2nd there after trying 1st a few times since all 1st delivered was almost unmanageable spin.

Chuck

Donnie Barnes · **Posted:** Wed Oct 17, 2007 9:27 am

You could stand an even bigger front bar, IMHO. That'll speed it up more than shocks if you're having to manage that much wheelspin...

I know it seems crazy, but I'd jump all the way to a 32mm or bigger if you can find one. If not, well, have one made.

--Donnie

JamesFeinberg · **Posted:** Wed Oct 17, 2007 10:00 am

Donnie Barnes wrote:

You could stand an even bigger front bar, IMHO. That'll speed it up more than shocks if you're having to manage that much wheelspin...

I know it seems crazy, but I'd jump all the way to a 32mm or bigger if you can find one. If not, well, have one made.

I was thinking the same thing. Going from a 24mm to a 27mm bar and still lifting the inside rear that much seems to indicate that more bar would be worthwhile.

Jim

Aaron Buckley · **Posted:** Wed Oct 17, 2007 10:02 am

Donnie Barnes wrote:

You could stand an even bigger front bar, IMHO. That'll speed it up more than shocks if you're having to manage that much wheelspin...

I know it seems crazy, but I'd jump all the way to a 32mm or bigger if you can find one. If not, well, have one made.

--Donnie

Donnie's likely right. We have 30mm bar on the front of the Crossfire (stock is 24 or 25mm), and the car is likely 300# or so lighter than yours. A 30+mm bar would keep the rear wheel on the ground a lot more. - AB

DickRasmussen · **Posted:** Wed Oct 17, 2007 12:34 pm

One trick an old pro taught me MANY years ago to manage inside wheelspin. Do as much of the needed turning as soon as possible and then unwind the steering asap to get the car pointed straighter and get the weight more evenly distributed on all four tires. This can be used to minimize wheelspin and/or corner exit push.

Chuck Branscomb · **Posted:** Wed Oct 17, 2007 1:38 pm

DickRasmussen wrote:

One trick an old pro taught me MANY years ago to manage inside wheelspin. Do as much of the needed turning as soon as possible and then unwind the steering asap to get the car pointed straighter and get the weight more evenly distributed on all four tires. This can be used to minimize wheelspin and/or corner exit push.

Exactly. With an open diff, the steering wheel angle is just as important as the throttle in the traction management equation. This has been a great learning experience for Jackie (along with reminding me of many years gone by when I used to autocross a non-LSD car).

I'm going to look into larger front bars since limiting front roll even more will help the camber situation up front too. However, if we're lifting the inside front tire now, it can only go higher with a stiffer front bar. Not sure how that will work out...

Karl Shultz · **Posted:** Wed Oct 17, 2007 1:58 pm

Chuck Branscomb wrote:

I'm going to look into larger front bars since limiting front roll even more will help the camber situation up front too. However, if we're lifting the inside front tire now, it can only go higher with a stiffer front bar. Not sure how that will work out...

Well, for starters, if it's already up in the air...what's the difference?

Second, if you put a set of shocks on it, you may be able to tune some of that wheel lift out, or at least subdue it somewhat...

Aaron Buckley · **Posted:** Wed Oct 17, 2007 2:02 pm

Karl Shultz wrote:

Well, for starters, if it's already up in the air...what's the difference?

Second, if you put a set of shocks on it, you may be able to tune some of that wheel lift out, or at least subdue it somewhat...

Yup. With the correct amount of compression in the rear (which likely means that OTS Konis may need to be revalved), you can control that amount of lift.

Personally, I wouldn't be too worried about it the way it is, unless you want to start running Tours/Pros. - AB

JamesFeinberg · **Posted:** Wed Oct 17, 2007 2:34 pm

Aaron Buckley wrote:

Personally, I wouldn't be too worried about it the way it is, unless you want to start running Tours/Pros. - AB

I tend to think the car might be a lot more fun to drive if you aren't constantly roasting the inside rear tire on corner exit. :whoknows:

Jim

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

I'd really like to try these to see how they stack up against the Hoosier R6 on track. Wish they would have made a 315 x 18. They went from 285 to 335 with no size in between.

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