That’s the query we regularly hear from the employees at Harris Hill Raceway–which we often go to a couple of times a week.
Generally we’re there for a full-on, multi-tire, back-to-back, bracketed comparability. As a rule, nonetheless, we’re merely visiting to run a single tire by means of its paces to expertise it as any typical fanatic would.
Select Correctly
When SCCA moved its emphasis away from R-comps to road tires a number of years again, the mantra was easy: “Make it simple, make it enjoyable.” And in these days, saving cash on consumables definitely added to the enjoyment. Road tires have been cheaper and extra sturdy, and the alternatives amongst them have been few.
Quick-forward to at present, and there are infinite tires to select from, every with extensively ranging traits. Fortuitously, we’ve achieved a lot of the heavy lifting for you with our Final Observe Tire Information–discover it on-line, whereas the abstract chart will be discovered on the finish of this text. All of at present’s prime tires have been scientifically examined and rated, so you may make an knowledgeable alternative. And people rankings are tweaked as we study extra in our weekly monitor outings.
For top-tier autocross use, you’re going to desire a quick tire whose compound activates rapidly in your software. Usually, which means a Yokohama Advan A052 or Bridgestone Potenza RE-71RS, rated A for each Tempo and Warmup. With its B score for Warmup, the Vitour Tempesta P1 could also be an possibility for a heavier automotive or hotter climate; it may also be an possibility in case you’re keen to throw away the primary run.
If time trials are your factor, speedy warmup is much less vital, as warmth will be constructed by means of further laps. The Nankang CR-S V2 joins the P1, A052 and RE-71RS as prime A-pace candidates, with the primary two giving extra fast laps based mostly on their Warmth Tolerance rankings. Against this, the Yokohama is infamous for being a “one and achieved” TT tire in lots of functions.
Briefly, it’s all about warmth administration: getting a tire into its optimum temperature window on your use case and maintaining it there so long as mandatory.
Getting Fitted
Generally the mannequin of tire you need doesn’t are available an optimum dimension on your automobile. You both have to decide on one other much less appropriate tire or compromise on dimension. One of many advantages of the Vitour P1 is a variety of fitments, with a promise of 65 sizes by the top of this 12 months.
SCCA Solo’s Road class brings with it restrictions on wheel width and camber, so the stiff-sidewalled RE-71RS tends to be a favourite there. Against this, Road Touring’s broad wheel fitments and plentiful camber make it an ideal playground for the A052. The distinctive, superwide P1 sizes promise to be favorites in CAM and XS, the place getting huge energy to the bottom is essential.
Getting ready for Battle
When you’ve chosen a tire, it’s vital to correctly put together it for the abuse we name motorsports. On the very least, you’ll want to wash off the shiny mildew launch lubricant earlier than it’ll ship any grip in any respect, particularly within the moist.
Even higher, a light preliminary warmth cycle will situation the rubber by realigning the molecules with stronger bonds. This course of makes the tire extra sturdy, constant and oftentimes quicker.
You may both pay your retailer to carry out this warmth biking by machine or do it your self. All of our take a look at tires get six laps at ever-increasing depth as much as about 90% tempo, whereupon they’re allowed to chill for at the very least 24 hours off the automotive. Alternatively, 40 minutes of freeway driving on a heat day may do the trick.
Tread Depth: Much less Is Extra
Purebred racing slicks, and their carefully associated R-comp cousins, ship the best ranges of grip for motorsports. A key characteristic is their skinny rubber tread caps–typical 4/32 inch–with no tread blocks to squirm round and generate extra warmth. This enables for softer compounds to be effectively supported, delivering higher grip and consistency over a session.
To optimize 200tw tires, this trait will be mimicked by carrying treaded road tires to decrease depths. Some tire fashions profit greater than others, however we’ve but to discover a road tire the place it had no constructive impact. Right here’s some examples.
Final fall, we pitted contemporary units of the highest 200tw tires in opposition to one another in a same-day take a look at. We then introduced every to the monitor, one after the other over the subsequent couple of months. Three months later, they’d all been worn to five/32 inch, albeit with some vital variations within the variety of laps it took to get there. The Nankang CR-S V2 was the sturdiness king, with the A052 and RE-71RS citing the rear midway again.
We then took the whole thing to Harris Hill Raceway once more for a head-to-head, same-day showdown to see how their relative efficiency had modified. All turned faster occasions that day, however the A052 and RE-71RS had caught as much as the P1. The CR-S V2 additionally improved by a full second, nevertheless it was nonetheless just a few tenths off.
One other information level comes from our current take a look at of the Hoosier Observe-Assault Professional, a 200tw tire that comes already molded to five/32 inch. In that take a look at, we in contrast the Hoosier to 2 units of the RE-71RS–one contemporary at 7/32 and the opposite worn to five/32. The 2 variations of the Bridgestone have been separated in tempo by the identical 1-second margin as our earlier P1 assessments.
Does this pattern proceed because the tire wears to even thinner depths? Our expertise tells us sure, however the enhancements come slower. We’ve run 1:24.0 laps on the RE-71RS and CR-S V2, each at 2/32 inch.
Want extra proof? Right here’s a long-term examine of the TrackAttack Professional. Notice that final tempo on any given day depends on monitor and climate circumstances, however the pattern right here is fairly clear.
With continued use, dealing with finally modifications for the more serious. All of these further warmth cycles slowly rob the rubber of grip to some extent that outweighs any profit from diminished tread squirm and lighter weight. The tire takes increasingly more operating to come back as much as temp and will get very edgy on the restrict. For some tires, it’s possible you’ll by no means get to the cords earlier than this occurs–the Falken RT660 is one.
A method round that is to shave the tires to the optimum depth earlier than operating. Whereas not as cost-effective for long-term utilization, it may be key to successful an vital occasion–in our case, the SCCA Time Trials Nationals. For the previous three years, we’ve fitted our Max 5 class-winning Honda CRX with Yokohama A052s shaved to 4/32 and warmth cycled by Tire Rack. For the reason that guidelines restrict rivals to at least one set of tires, ours have been of their candy spot for the complete four-day occasion.
If you happen to do select to pre-shave your tires, you possibly can anticipate to realize a bit extra efficiency after they’re run for one or two classes. This ultimate operation establishes the wear and tear sample for every nook of the automotive, in line with stress and camber settings.
One of many key advantages of decrease tread depths may also be a draw back, nonetheless. By producing much less warmth, the tire is extra constant–but in addition takes longer to activate. So, in case you’re autocrossing on a cool day with a comparatively gentle automotive and a single driver, it’s possible you’ll be at an obstacle. The Tread Depth Sensitivity column within the Information is your key right here. Consider it as a modifier on the Warmup column.
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