On average how much will your lap times drop going from street tires to R comps?

[Evergreen Dan]

Interesting. I find that fresh R-comps are about 2 seconds faster than the old worn-out set (at, say, NHIS, about 1.6 miles). You'd think that old R-comps would still be faster than fresh stree tires (until they are really corded, anyway).

[tmachine]

Here is a link to a R-comp calculator for what it's worth...
http://www.ncr-pca.org/autocross/r-tires.htm

.

[Emre]

On the other hand, you'll never want to go back to street tires on the track once you've had R-comps on your car.

Dunno. I've been tracking for quite a few years and instructing for maybe 7 years now. I've personally gone back to street tires after running R-comps for a few seasons.

First of all, this is HPDE ... not a racing. Outright lap times don't matter to me. Fun matters to me. And I have more fun sliding a car around the corners (easy as pie on good street tires). It's also more fun to drive to the car to the track, tear it up all weekend, and then drive it back home. I don't enjoy wrenching at the track: even swapping wheels/tires gets pretty old the 100th time you do it!

But the main factor for me was the wear and tear. I was literally doing one event each weekend of the summer for a few seasons. I got a little tired of destroying wheel bearings, changing control arms, and burning up rear diffs. All of that stopped when I gave up R-compounds. Running street tires is a LOT easier on the car, which lets me spend more time in the car and less time under the car.

See sig, you can't do that on street tires.

You absolutely can do that. You just need the car to be set up properly and you need to run good tires.

Emre

[CMM3]

Interesting discussion on the intent of HPDE's, timing laps and potentially switching to R compound tires. I personally think a lot depends on were you might like the sport to lead you and what you're willing to invest into it to get there. There are plenty of folks who attend HPDE's with mildly modified cars (mostly for safety concerns ) and get years of enjoyment and driver skill advancement from it..period. Then there are those, perhaps the majority who are view the sport as something of a never ending pursuit to not only to advance driver skill but also to continually improve their cars to enable them to improve lap times as a combination of this. It's generally agreed that a fast driver in a slow car is a better driver than the reverse. But I believe that once you achieve a reasonable level of competence behind the wheel on the track there comes a time when you may want to challenge yourself by growing into some improvements you've made to the car, even if this means you might have to step over the limits of your driving to call it, catch up with the cars capability. If one never exceeds the limits how does one know were the limits lie and how to edge up close to them and/or recover when they are exceeded. There have been plenty of answers on how much faster R compound tires are but I think the more important question is how much time and money are you willing to invest. If obtaining car control skill is the ultimate goal then there is no better way then attending advanced skills schools conducted on wet skid pads in parking lots by most BMW chapters. If improving your car is part of the hobby then I'd say be smart about it. For someone with a few dozen or so HPDE days that has been showing steady progression and already made the other standard upgrades to their car, sway bars, shocks, springs etc then R compound tires may be the next logical step. I've been instructing now for 20 years and with a student that is showing good judgement and basic car control skills I'll try and push them a little and might encourage them to make additional improvements to their car. On the other hand if I have a student that is trying to drive fast poorly and relying on traction control to keep their car on the track I'd never encourage them to improve their car. In fact I've made log book recommendations for a student to be moved to a lower run group, turn the traction control off and begin the learning process all over. The ideal of anyone not easily having access to their lap times is insane. The genie is out of the bottle as far as this is concerned so perhaps the best approach is to acknowledge this and treat it as a learning tool along with making upgrades to their car including R compounds, something that each HPDE student should discuss with an instructor and make an educated decision on.

[TXBDan]

My first time in R1-Ss I dropped four seconds in three laps compared to NT01s the session before. This was at Palmer.

On point: if you want to go fast and compete, you need rules. If you’re just modding your car to infinity, what’s the point? I’d youre competing within a rule set, that’ll influence your tire choice.

With no classing, no rules, who cares just run NT01s.

[joenationwide]

I must challenge that statement, sir!



This is on Yoko Advan Neova ADO7s street tires.



I've heard that in autox, R-comps are worth about 2 sec. on a 60 sec. course (over street tires). Of course there are lots of variables, and lots of pseudo R-comp/street tires now (Neova AD07s, Stones RE01Rs)...

Damn, this thread is so old I posted in it over 11 years ago! Feel free to ignore my trip down memory lane.
I was just starting to do track days back then, after 3 solid years of autoxing.

I starting instructing in 2008.
Racing in 2014.
I used to drive my car to the track every event until I started racing.

My rule was I would only run on R-comps if I had a chance to win more R-comps.
Otherwise I would always run HPDEs on street tires.
I think it makes you a better driver, and it is far cheaper.

I still believe that today, even though I primarily run on R-comps.
But nowadays R-comps are free and I still pay for street tires.
And I'm now trying to find tenths at race pace during practice, so I need to be at race prep.

But for having fun in an HDPE, stick with street tires. You'll get faster that way.

[olemiss540]

My first time in R1-Ss I dropped four seconds in three laps compared to NT01s the session before. This was at Palmer.

On point: if you want to go fast and compete, you need rules. If you’re just modding your car to infinity, what’s the point? I’d youre competing within a rule set, that’ll influence your tire choice.

With no classing, no rules, who cares just run NT01s.

The point is SPEED. The all allusive and abusive mistress. Also, building cars can be fun. Shopping parts. Buying good deals. Talking/working/chasing with our friends and fellow enthusiasts.

My e36 racecar is modded to hell and back for no other reason than fun. No idea what (if any) rule set it follows, but holy hell is it a lot of fun to slide and scream at 9/10ths. It is a hell of a lot safer than the brand new 750hp corvette out there as well while being just as fast and MUCH cheaper.

We all have our own personal boundaries when it comes to fun/$$$ and so I dont fault or judge those running r7's at HPDE's just to chase around their buddies/friends with built supercars. HAVE FUN, BE SAFE, BE COURTEOUS, and try to keep the judgement toned down to a minimum, thats what the Porsche guys are for.

P.S. NT01's are my all time favorite HPDE tire. But not because they are slow, but because they are the least amount of maintenance. Long life and dont have to mark down heat cycles into a notebook. If they made a new tire that was twice as fast and lasted as long, you bet to hell it would be mounted on my wheels.

Currently running Maxxis RC-1's since they come in the sweet sweet sizing of 275/35/17's from C4's of yesteryear.

[aeronaut]

^ good post.

I'm modding my car this winter, but I honestly don't want to make it faster. Just more reliable and more fun. I have a few instructor friends that I always go out with, and we are dead nuts even on most tracks, so we're all pushed to learn to drive better.

I did have to switch from NT01 to Toyo RRs to get the pace I need. The RR's are awesome too..but a touch more expensive and less wear. They DO last well through many heat cycles, all the way to the cord. I'm thinking of going to a wider rim with flares, so I can get back to NT01s and maybe/hopefully maintain speed.

[olemiss540]

Yes. Flares for max fun. My last 2 e36's had flares, the first with a set of very nice Hard Motorsports flares. Current car has the most absurdly hacked up Chinese ebay "generic" plastic flares.

275/40/17 NT01's are a lot of fun, just have to make sure to have adjustable FCABs in case of minor castor tweaks for rubbing. Have to run taller ride heights but they last FOREVER considering the weight/tire ratio. Maxxis 275/35/17's are my new goto as they are easier to fit, and look like they are going to last as long. They are just as fast (or maybe even a touch faster) as NT01's, but are not as fun since they do not like slip angle AT ALL. Had to tidy up my driving style, but Road Atlanta last weekend was a HOOT!

[Haifisch M3]

Yes. Flares for max fun. My last 2 e36's had flares, the first with a set of very nice Hard Motorsports flares. Current car has the most absurdly hacked up Chinese ebay "generic" plastic flares.

275/40/17 NT01's are a lot of fun, just have to make sure to have adjustable FCABs in case of minor castor tweaks for rubbing. Have to run taller ride heights but they last FOREVER considering the weight/tire ratio. Maxxis 275/35/17's are my new goto as they are easier to fit, and look like they are going to last as long. They are just as fast (or maybe even a touch faster) as NT01's, but are not as fun since they do not like slip angle AT ALL. Had to tidy up my driving style, but Road Atlanta last weekend was a HOOT!

so the 275/40/17 NT01's were to large in diameter to fit the e36?

[olemiss540]

They definitely fit. I ran them for a full season with zero issues. Just have to tweak ride height and possibly adjust front castor (for bumper clearance). On a dedicated track car is no issue. I just preferred the RC-1's to lower ride height while also improving gearing for around the same price.

[Haifisch M3]

what about gearing ? did you feel the difference due to larger diameter?

[olemiss540]

Sorry, but went to a totally new car with a totally different gearing setup (from 3.38 s50 to a 3.91/T56/LSx) so not sure how big of an impact. According to: https://tiresize.com/gear-ratio-calculator/ it would change a stock 3.38 to a 3.53, so pretty big difference!

[Haifisch M3]

how do the Maxxis 275/35/17's compare to the NT01s as far as heat cycling.
That was always supposed to be the strenght of the NT01s