200-treadwear tire test | Bridgestone Potenza RE-71RS vs. Falken Azenis RT660

Andy
By Andy Hollis
Sep 6, 2022 | Tire Test, tires, Bridgestone, 200tw, RE71-RS, Bridgestone RE-71RS | Posted in Product Reviews , News and Notes | Never miss an article

Photography Credit: Andy Hollis

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Things change quickly in the world of 200tw street tires. With so many motivated manufacturers vying for a share of a myriad of motorsports venues, today’s cutting-edge technology is tomorrow’s also-ran. 

During the last 20 years, BFGoodrich, Bridgestone, Falken, Kumho, Toyo and Yokohama have all cycled through as the dominant brand, with Bridgestone returning to prominence in 2015 with its Potenza RE-71R. Thanks to an almost perfect blend of response, grip and longevity, Bridgestone built a huge following for both motorsports and street use. 

[Ultimate track tire guide | 200tw, 100tw, street-legal track and R-comps]

The RE-71R was filling podiums in autocross, time trials and even endurance racing. But when 2020 came around, word filtered out that production of the RE-71R had ceased, and there was no replacement coming to the U.S. Amateur racers throughout the country were stunned.

[200-Treadwear Tire Test | Goodyear F1 Supercar 3 and Michelin Pilot Sport Cup 2 vs. the Outgoing Bridgestone RE-71R]

Well, race fans, happy days are here again: Bridgestone is back. Its new Potenza RE-71RS was developed in Japan specifically as a track day tire with little consideration for the wider U.S. market–but that’s how its predecessor came to be, and that one turned out to be quite versatile.

Would the RE-71RS share that same versatility or would it be a one-trick pony? As a source confided in us, that was a key concern for Bridgestone’s American arm and a reason why the company didn’t initially import the new tire. 

During Bridgestone’s two-year hiatus, fans looking for the same type of responsive feel gravitated to the then-new Falken Azenis RT660. There they found similar performance, especially when compared to alternatives from Yokohama and BFGoodrich. 

[200-treadwear tire test | Falken RT660 vs. Yokohama A052 vs. Nankang CR-1]

This shouldn’t be a surprise, given that the Bridgestone and Falken employ similar internal belt packages and tread design. Comparing the new Bridgestone against the Falken seemed the most appropriate. 

Not all the sizes on the new Bridgestone’s roster would be available on day one, but we were able to score a set of 245/40R17 tires early–the perfect size for our Triple Threat ND-chassis Mazda Miata. Why a Miata for tire testing? We’ve found that the larger the performance envelope, the more dangerous and challenging it becomes to take unknown tires right to the limit and keep them there. Our experience, however, tells us that the relative results do scale up.

For the Falkens, we went with the 235/40R17 size, the variance coming from the desire to keep the tread width the same. The Falken runs very wide, with the 235 putting down the same contact patch as Bridgestone’s 245. We mounted up all the test tires on 17x9-inch 6UL wheels from 949 Racing. 

Harris Hill Raceway again served as the test grounds. Running it counterclockwise provides a good mix of big sweepers, tighter 180s and two long straights ending in hard braking events. Both sets of tires were given a first heat cycle several days before the test.

Test day dawned partly cloudy with temps in the mid-80s. Fortunately, the track was relatively clean and rubbered in from heavy use the previous four days. We unloaded and got right down to business.

Track Results

Falken Azenis RT660

  • best lap: 1:29.4
  • $234 (235/40R17)

Since we’ve run them before, we first went out on our fresh Falkens. Solid grip, responsive handling and a fairly talkative nature are its strong suits, and we felt right at home. On this warm day, our first three laps were the quickest before heat soak caused a reduction in grip, slowing us about half a second for several more laps.

Bridgestone Potenza RE-71RS

  • best lap: 1:28.1
  • $228 (245/40R17)

We then headed out on the Bridgestones and immediately noticed a stronger on-center feel, receiving more tactile feedback with lateral loading. Even more impressive was the exceptional combined loading under trail braking and corner exit power-up. Those acceleration gains paid dividends down each of the three straights, which added up quickly in our underpowered Miata. The first lap out on stone-cold tires produced a time that was more than a second quicker than the Falken’s best. The next two laps also beat the Falken yet were substantially slower. Subsequent performance then stabilized at times similar to the Falken’s.

Falken Azenis RT660 (retest)

  • best lap: 1:28.8

Bracketing our test to look for track or driver improvements, we headed back out on the Falkens. Average times were just a couple tenths quicker, but all the dots connected well on the second pass for a single flyer. Data analysis of that lap later showed driver confidence improvements in two very tricky areas: the high-speed entry to the Turn 8 sweeper and the trail-braking zone into Turn 2. Overall, though, the relative rankings were clear.

Bridgestone Potenza RE-71RS (retest)

  • best lap: 1:28.3

We could have packed up at this point, but we were curious about that cold-tire “magic lap” delivered by the RE-71RS. Could we repeat it even though the tires were no longer as cool as when we first started the day? We headed out for another session and came up just a couple tenths short. But we did do it twice in a row this time before times again fell off.

Who Won Here?

Bridgestone Potenza RE-71RS (left) and Falken Azenis RT660 (right). Photography Credit: Andy Hollis

The day’s results took us by surprise at first, as we expected a much closer battle. In fact, previous sessions with this car on RT660 tires under similar conditions produced lap times that rivaled the new RE-71RS. 

What was different this time? Tread depth. In addition to benefiting from heat cycling, the Falken performs better at lower tread depths. In the past, our quickest times have always come once the tread got below 4/32 inch. 

Of course, the RE-71RS may very well find even more time once worn or shaved. That said, its predecessor, the RE-71R, did not improve significantly at lower depths. Which will it be? The answer to that question will have to wait for another day.

But Bridgestone has built another winner. We love how this tire feels on track, and its early lap heroics bode well for both time trial and autocross competitors. While we wish we hadn’t had to wait, sometimes you need to. Welcome back, Bridgestone.

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Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
7/6/22 4:49 p.m.

David S. Wallens
David S. Wallens Editorial Director
7/6/22 6:15 p.m.

So, some behind-the-scenes info.

Our test tires only landed in the U.S. around June 24. Bridgestone needed a few to unload and ship them our way. They arrived at Andy's shop late this past Thursday.

Tires had to be mounted and balanced. Then we could heat cycle and allow the tires 24 hours to cure. Testing took place yesterday. Then figure a bit for data analysis, writing, editing and proofing. Whew. 

David S. Wallens
David S. Wallens Editorial Director
7/6/22 6:16 p.m.

We have some wider ones on the way, too, but they're still on the way. 

Matt Huffman
Matt Huffman New Reader
7/6/22 7:15 p.m.

I run the kumho v730 and appreciate the fact that it's pretty fast and consistent for autocross,  TT, and extended HPDE sessions.   I was hoping the Bridgestone would be more similar to the v730 than the a052.  I'm also surprised the rt660 fell off after a few laps because many folks say it retains speed.   Perhaps tread depth is a key variable here.  The v730, with so little tread,  doesn't heat up as quickly and the compound likes heat so no surprise it tolerates extended lapping. 

jstein77
jstein77 UberDork
7/6/22 9:19 p.m.

So you haven't yet run the RE-71RS head-to-head against the A052?

Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
7/6/22 10:11 p.m.

In reply to jstein77 :

Yes we did--it's the sidebar next to/under this story depending on what device you're on. 

JMcD
JMcD New Reader
7/7/22 10:12 a.m.

Y'all are the best. Did the autocross tires get the same heat cycle treatment as Andy's?

beatus
beatus GRM+ Memberand New Reader
7/7/22 11:31 a.m.

I appreciate what you're trying to do with the 235 vs 245, but I think it misses the point quite a bit. No sanctioning body I'm aware of normalizes for measured tire width, they class based on stated tire size.

IMHO this makes the more relevant comparo a 245 vs 245, even if the 660s run significantly wider because they end up living in the same class.

Instead, there needs to be some reading between the lines that the re-71rs is still faster 245vs245, but it's a guess instead of real data.

G_Loc
G_Loc New Reader
7/7/22 1:20 p.m.

Any idea when wider sizes will be available?  I had ordered 295s from Tire Rack on 4/20 right when they became available.  Delivery date was supposed to be early June, then got pushed back to July, and now there's no ETA at all.  Heck they don't even show up as an available size anymore.  Had to go with an alternate tire for the time being.

David S. Wallens
David S. Wallens Editorial Director
7/7/22 1:28 p.m.

In reply to G_Loc :

Sorry, I don't have any info regarding future shipments. 

malibuguy
malibuguy GRM+ Memberand HalfDork
7/7/22 6:57 p.m.

damn thats consistently significant.  I am diehard on the Falkens, but this had me look up to see if the stones were in my sizes and (surprisingly) they werent.  Good, I didnt feel like peeling off the Falken stickers

thashane
thashane GRM+ Memberand Reader
7/8/22 12:08 a.m.
beatus said:

I appreciate what you're trying to do with the 235 vs 245, but I think it misses the point quite a bit. No sanctioning body I'm aware of normalizes for measured tire width, they class based on stated tire size.

IMHO this makes the more relevant comparo a 245 vs 245, even if the 660s run significantly wider because they end up living in the same class.

Instead, there needs to be some reading between the lines that the re-71rs is still faster 245vs245, but it's a guess instead of real data.

Some cars can't run the maximum tire for the class. I prefer it this way, with actual width. 

I'm impressed to see them that much quicker. Prices appear to be in the A052 range, with 660s being about $60 less A TIRE (atleast $64 for 225/45r17s). TR has a mail in rebate for $90, but even if you get them through Costco with $150 rebate, the 660s are still $90 less for a set of 4.

Overall-pretty excited to have a new top 200tw contender, and interested to see how they preform.

pinchvalve (Forum Supporter)
pinchvalve (Forum Supporter) GRM+ Memberand MegaDork
7/8/22 8:23 a.m.

I had issues with the center rib on the Falkens coming off, so badly and so quickly that Tire Rack had to issue refunds. I have seen the same issue from others online as well, with some seeking replacements and others saying that is normal for Falkens.  I also know of many who have had no problems and claim they wear as well as anything else. What was your experience on the Falkens? They look fine in the photo if that is an after photo, this is mine after about 2 autocross runs. 

DeanM
DeanM GRM+ Member
7/8/22 8:43 a.m.

As a street class autocrosser, I'm not sure what my takeaway is here... A052 might as well not exist anymore in my sizes, so I would have loved to see the sidebar focus on these VS RT660 as well. But I guess there are some classes who can still find A052 in their sizes

DeanM
DeanM GRM+ Memberand New Reader
7/8/22 8:45 a.m.

In reply to pinchvalve (Forum Supporter) :

What car and how much camber? My 660 don't look quite that bad on a heavy, low camber car... but that's exactly how RE71R used to look for me and it was never a problem 

hunter47
hunter47 Reader
7/8/22 11:30 a.m.

In reply to DeanM :

Same here, I run them on a 2020 WRX with -2 degrees front camber/-1.5 degrees rear camber and while I get a little delam I haven't gotten anything that badly. 

Defined motorsports
Defined motorsports SuperDork
7/8/22 4:23 p.m.

when information you might want sits behind a pay wall. 

CSSharpe
CSSharpe New Reader
7/8/22 10:16 p.m.

In reply to JMcD :

Yes, it is in the article.  Heat cycled at MSR Cresson.

CSSharpe
CSSharpe New Reader
7/8/22 10:28 p.m.

In reply to pinchvalve (Forum Supporter) :

Did you heat cycle them prior to competition?  

jbrauer11
jbrauer11 New Reader
7/11/22 1:56 p.m.

In reply to beatus :

Clearly you're unaware that NASA Time Trials AND Super Touring race classes both use tire width templates, not stated tire size, specifically because stated tire sizes are so frequently inaccurate.

pinchvalve (Forum Supporter)
pinchvalve (Forum Supporter) GRM+ Memberand MegaDork
7/11/22 2:27 p.m.

In reply to CSSharpe :

I did not have them heat cycled by Tire Rack the first time, but I put some street miles on them. With the second set, I did have them cycled and they did the same thing. That photo is BEFORE they got worse BTW. With RE71r and Rivals, I never heat cycled or ran them before competing and never had a problem. This was on my 2800# Fiesta ST with 3-degrees up front. 

David S. Wallens
David S. Wallens Editorial Director
7/11/22 3:58 p.m.

These are the RT660s on our Miata after about 16 autocrosses and a few thousand street miles. Tires were heat cycled on the street before that first event.

David S. Wallens
David S. Wallens Editorial Director
7/11/22 3:58 p.m.

(PS: I know that photo stinks–I'll get a better one and some tread depth numbers for everyone later today.)

zm2
zm2 GRM+ Memberand New Reader
7/13/22 10:33 a.m.

In reply to David S. Wallens :

Nice initial review. Will be great to see how they hold up to heat & wear vs their peers in longer-term reviews. Plus, I'm hearing the 71RS's wet performance is excellent.

Is driving a couple hours the night before on a new set of 71RS's a good enough heat cycle for a road track weekend like WGI? Or, would proper heat cycling yield that much more grip/longevity? No time trials, just focused on HPDE and open track consistency & longevity.

David S. Wallens
David S. Wallens Editorial Director
7/13/22 10:48 a.m.

In reply to zm2 :

Thank you. 

Look for more on heat cyclings on the site really soon, but the experts (John R. at Tire Rack) says to rest the tires for 24 hours after that first drive in order to generate a true first heat cycle. Will overnight do it? I'm not sure but he always says 24 hours. He does say that an hour on the highway generates enough heat. It's that sitting that seals the deal. 

I heat cycled my Falkens, and they're wearing like iron. 

As we get more info on how the Bridgetones wear, we'll share it. 

malibuguy
malibuguy GRM+ Memberand HalfDork
7/16/22 12:41 p.m.

In reply to pinchvalve (Forum Supporter) :

I have 2 sets (different sizes) of Falkens and NONE have had that issue.  I have little over 3* on a FWD MacStrut car, so take it FWIW.  One set has a year of autoX, the newer set has only seen a handfull of events this year so far

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) GRM+ Memberand PowerDork
9/6/22 10:36 p.m.

I'm waiting for cooler/wetter weather to try mine. I heat cycled them last weekend, then stacked them next to the rivals to compare width. 
225/45-15 rivals on the left, on the right 205/50-15 RE71rs. Lots wider than the old ones. Both are on six inch wheels. 
 

Bigben
Bigben Reader
9/9/22 7:18 p.m.
Floating Doc (Forum Supporter) said:

I'm waiting for cooler/wetter weather to try mine. I heat cycled them last weekend, then stacked them next to the rivals to compare width. 
225/45-15 rivals on the left, on the right 205/50-15 RE71rs. Lots wider than the old ones. Both are on six inch wheels. 
 

Can you please post comparison pictures showing the wheel fitment of those two sets of tires?

Since they're both on 6" wheels, does the 225 seem to provide any benefits for you? Right now I'm limited to a set of 6" wheels and a set of 6.5" wheels and I'm trying to figure out if getting 225/45 is worth it vs 205/50

APEowner
APEowner GRM+ Memberand UltraDork
9/9/22 9:15 p.m.
David S. Wallens said:

In reply to zm2 :

Thank you. 

Look for more on heat cyclings on the site really soon, but the experts (John R. at Tire Rack) says to rest the tires for 24 hours after that first drive in order to generate a true first heat cycle. Will overnight do it? I'm not sure but he always says 24 hours. He does say that an hour on the highway generates enough heat. It's that sitting that seals the deal. 

I heat cycled my Falkens, and they're wearing like iron. 

As we get more info on how the Bridgetones wear, we'll share it. 

Any idea when we might see more on heat cycling or is it up somewhere and  I missed it?  I'm thinking about renting the track and having someone heat cycle multiple sets of tires and I'd really like to better understand the science and the optimal way to do it.

hunter47
hunter47 Reader
9/9/22 10:18 p.m.

In reply to APEowner :

FWIW tire rack offers heat cycling on the RT660s for $20/tire. Gonna be doing that for my next set and not worry about it. 

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) GRM+ Memberand PowerDork
9/10/22 10:40 a.m.

In reply to Bigben :

With those wheel sizes, sounds like an MR2. 
 

As to your questions, more tire is always an advantage. The rivals are a bit pinched on a six inch wheel, but it's functional. I'm just continuing with the way my Miata was set up when the previous owner had it, which worked well enough to trophy at Nationals. 
 

I won't have the Bridgestone's off of the tire rack for a while, probably until fall. Here's a picture of the 225/45–15 rival on a 6 inch wheel. It's set at 34 pounds/inch in the photo.

Same size tire, stock Miata 6 inch wheel. Pressure is about 28 pounds.

Bigben
Bigben Reader
9/10/22 1:57 p.m.

In reply to Floating Doc (Forum Supporter) :

Thanks for the pictures and info.  Maybe it is just the angle of the photos, but the tire on the stock Miata wheel looks more pinched than on the aftermarket wheel.

To clarify on my wheel constraints they are going on an Opel GT for the Challenge.  The size constraint is just that I haven't found anything wider than 6.5" wheels for a price that fits in the budget.  I have a set of Miata wheels just like the ones in your picture that were $60 for the set and some unknown brand 6 spoke 6.5" wide wheels that were $100 for the set.  I guess I  do have a third option of Kosei 17x7 but 17" tire options that aren't too tall are limited.

APEowner
APEowner GRM+ Memberand UltraDork
9/10/22 7:23 p.m.
hunter47 said:

In reply to APEowner :

FWIW tire rack offers heat cycling on the RT660s for $20/tire. Gonna be doing that for my next set and not worry about it. 

Thanks for that.  I've thought about doing that but I go through 5 sets of tires a season and that's a pretty significant chunk of change.  I don't know if the increase in tire life is going to make it worthwhile.

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) GRM+ Memberand PowerDork
9/11/22 4:33 p.m.

In reply to Bigben :

Remember, the tire on the stock wheel is carrying the weight of the car and is six pounds lower.

David S. Wallens
David S. Wallens Editorial Director
9/13/22 10:54 a.m.

FWIW, we have some wide v narrow wheel and tire tests in discussion. (I've said too much.)

Bigben
Bigben Reader
9/15/22 12:59 a.m.
David S. Wallens said:

FWIW, we have some wide v narrow wheel and tire tests in discussion. (I've said too much.)

Do you think you can speed that up? I need to make a decision on tires for the Challenge. laugh

Joking aside,  I'm wondering about 205/50 vs 225/45 RT660's on the 6.5" wheel, trying to determine if it is worth the extra cost and 2 lbs per tire for the 225 if running a narrow wheel.  According to the specs on tire rack the 225 is only a half inch wider than the 205 and that is with the 205 being measured on a 1" narrower wheel than the 225. This makes me think that if the 225 is stuffed on to a 6.5" wheel the section width would end up pretty close to the same as the 205.

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) GRM+ Memberand PowerDork
9/15/22 6:16 a.m.

In reply to Bigben :

I haven't had a set of 660s yet, but I know that they run wide for their sizes. I'd go with the 205. 

David S. Wallens
David S. Wallens Editorial Director
9/15/22 9:29 a.m.

In reply to Bigben :

That test is coming. I can't promise it before the Challenge, but it's coming!

Do you have the room for 225s? I run 205s on the Miata, and they rub. But I also have my fender liners and unrolled lips. 

Bigben
Bigben Reader
9/15/22 10:04 p.m.
David S. Wallens said:

In reply to Bigben :

That test is coming. I can't promise it before the Challenge, but it's coming!

Do you have the room for 225s? I run 205s on the Miata, and they rub. But I also have my fender liners and unrolled lips. 

Yeah 225 will fit. I have aged (probably 2016 or 2017 mfg date) 245 Hoosier S80 slicks squeezed on to the 6.5" wheels right now. I ran those at the 2019 Challenge and they only rub a little in a narrow range near full lock.

Modular
Modular GRM+ Memberand New Reader
9/19/22 10:37 a.m.

In reply to David S. Wallens :

I'm curious to learn the results on the heat cycling. I'm also, frankly, not convinced a driver can legally generate enough heat in the tire on any public road to heat cycle on the highway. Hopefully that's something that's tested as well!

Bigben
Bigben Reader
9/21/22 12:04 a.m.

My first ever pair of new autocross tires just arrived courtesy of Tire Rack. (Yes I am that cheap that I've never bought new race tires) I purchased a pair of 205/50 RT660 to test fit. If I decide I can go wider on the wheels then I'll put the 205's on the front and get 225's for the rear. 

Here are the 205/50-15 Falkens next to 245/45-17 Sumitomos. Theoretically based on stated width the pair of 245s should be 3.15" wider than the 205s but they are only 2.625" wider. If we assume the 245s are true to size then the 205s are closer to being a 215.

I measured the distance between beads of the relaxed RT660s to be 6.5" so definitely a nominal fit on 6.5" rims and a little pinch on 6" rims. What I found interesting is the section width and tread width both measured wider than what the spec sheet says. I measure a tad over 8.5" for section width and 7.5" for tread (measured between the outermost points of tread grooves.)

dps214
dps214 Dork
9/21/22 12:10 a.m.

Those specs are measured as installed on a 6.5" wheel in this case. .1" wide on section width measuring unmounted tires seems about right. Tread width is more of an arbitrary measurement, not surprising falken/tire rack chose different points to measure from than you did.

And yes, 8.4" section width means they're just under the nominal size of a 215 width tire (8.46").

Bigben
Bigben Reader
9/23/22 12:27 a.m.
David S. Wallens said:

In reply to Bigben :

That test is coming. I can't promise it before the Challenge, but it's coming!

Do you have the room for 225s? I run 205s on the Miata, and they rub. But I also have my fender liners and unrolled lips. 

205s on Miata wheels = Lots of room.  (I could definitely use a deeper wheel and/or wider tire.

Mounted on the 6" wheels, section width measures 8.375"  They do look like they would be more at home on a 7" wheel but the fit doesn't look too bad on the 6".

Andy Hollis
Andy Hollis
9/28/22 6:48 a.m.

Just came across this now (David, you need to lmk on these things!)...

Regarding 205 vs 225 on a 6.5...205 all day long.  The 225 will work, but provide almost no benefit.  It will also feel sloppier, though in a track situation may stay a bit more consistent across a session.

In the past, we've tested wheel widths with street tires several times (David forgets these things :) ).  Wider wheels always provide a benefit, while wider tires on the same wheel do not.  The rule of thumb for street tires is to increase wheel width until it matches the tread width (not section width).  Sometimes another .5-1 inch can also help...depends on the tire.  Yoko A052 is one that likes this.

Past tests showed a 225/45-15 and 245/40-15 ran the same lap times when mounted on 9" wide wheels.  Putting the 245 on a 10 netted another half second. 

Andy Hollis
Andy Hollis
9/28/22 6:52 a.m.

And here are some notes on heat cycling: https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=66

And this from Phil's Tire Service:

The Nankang AR-1, CR-S, SL-1, and NS-2R will greatly benefit from an initial “break-in” heat cycle, (commonly called “scrubbing in”) before the tires are pushed, for better performance. Set cold air pressure at an adequate psi to handle the weight of the car. On track, gradually increase speed subsequently for a minimum 3-4 laps, not to exceed 85% capacity*, followed by an off the car cooling period of not less than 24 hours, which will result in a much improved tire life and on track performance for future sessions.

If this procedure is not possible due to losing on track sessions – PTS can heat cycle your tires prior to shipping them to you, which will reduce (not replace) the break in procedure required for AR-1’s and CR-1/CR-S models.

This is a proven procedure to enhance and improve your on track experience, gathered from many years of our own racing experience and track events, as well as the many experienced drivers we have worked with over the years.

*2 – laps 50%, 1 – lap 75%, 1 – 85%, 2 – cool down laps 50%

APEowner
APEowner GRM+ Memberand UltraDork
9/28/22 8:15 a.m.

In reply to Andy Hollis :

Thanks Andy.  

Bigben
Bigben Reader
9/28/22 6:59 p.m.
Andy Hollis said:

Just came across this now (David, you need to lmk on these things!)...

Regarding 205 vs 225 on a 6.5...205 all day long.  The 225 will work, but provide almost no benefit.  It will also feel sloppier, though in a track situation may stay a bit more consistent across a session.

In the past, we've tested wheel widths with street tires several times (David forgets these things :) ).  Wider wheels always provide a benefit, while wider tires on the same wheel do not.  The rule of thumb for street tires is to increase wheel width until it matches the tread width (not section width).  Sometimes another .5-1 inch can also help...depends on the tire.  Yoko A052 is one that likes this.

Past tests showed a 225/45-15 and 245/40-15 ran the same lap times when mounted on 9" wide wheels.  Putting the 245 on a 10 netted another half second. 

Thanks for joining the conversation Andy and providing insights. I realize that the wider tire loses benefits on a narrow wheel for road course or autocross. The problem I'm trying to solve is forward bite on corner exit and drag launch without significant negative impact to autocross times. Right now I'm stuck with a 6 or 6.5" wheel (6.5's are probably about 2 lbs heavier per wheel) because that's the best I've been able to find in budget.

The question in my mind is do I stuff 225 (or even 245s) on the rear only with the narrow wheels and keep 205's on the front with the hope of turning the same autocross times as running 205's all around and being able to air down the wider rear tires for more contact patch during the drag launch? Or would I likely shoot myself in the foot in the autocross without seeing the benefit of much additional forward bite in the drags? (2100 lb turbo car likes to spin when boost hits)

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