Topic: Some wheely important questions about tires.

I'm trying to get a RX-8 ready for Gingerman.  It's raced before at Barber in '18, and at that track we ran high performance all-seasons that did pretty well, but they're quite chunked now and I wouldn't rely on them for another race.  I've had a bit of a hard time finding good lemony race tires for this car and I have a few quesions about tires and wheels I hope the experts (this means you) can help me with.

1) The obvious "which tires are best" question that everyone asks all the time.  I've raced Falken Azenis R615K before, but on a much lighter car (~2300lbs vs. ~3000lbs) and wondered if anyone had some good input on how they hold up on middle-weight cars.  It's rear-wheel drive, but not high torque, so it's not like we'll be spinning the tires coming out of every corner.  Does someone have a perfect suggestion for another tire model that performs better somehow?  We're not rich so money is definitely an object here.

2) Running non-OE-size tires: The OE size is 225/45R18, but for some reason it's really hard to find Lemons tires in that size.  The aforementioned Azenis are easily available in 225/40 (for reasonable prices even), which would decrease the outer diameter somewhat.  Is this bad?  The only effects I can think of off the top of my head are decreasing the total amount of rubber in use (so reduced life?), and effectively lowering your final drive ratio.

3) Wheels: I assume we'll be mounting new tires on our existing wheels, but are considering an extra set of wheels so we can keep our old tires as backups (we may also buy a couple extra race tires and have them mounted for spares).  For a car this weight, is it safe to just buy the cheapest alloys at TireRack or other retailer?  Can we run cheap steel wheels?  Or do we need to look for high-quality racing wheels?  OEM wheels are really hard to find.

Thanks.

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Re: Some wheely important questions about tires.

There are a million threads on here about best tires, but the Azenis are pretty good across a wide range of cars.  Any 200 TW tire will be better than an all season.

As far as moving from a 45 series to a 40 series you shouldn't lose anything other than a half inch in sidewall.  They should last the same. You can use this to see what the change in tire size means to your width and height.  https://tiresize.com/calculator/

If you post your wheel bolt pattern, size and offset, someone might know another OEM take off that might work.  OEM wheels are typically pretty light and you can find them cheap on craigslist and junkyards.

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Re: Some wheely important questions about tires.

I'd try to find OEM wheels or high quality aftermarket. Heavy, weak aftermarket Chinesium alloys aren't what I want to rely on cornering at speed. They don't need to be OEM Mazda if some other car's wheels fit, but I've seems some aftermarket ones that I wouldn't trust to go to the grocery store,

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4 (edited by Lemon_Newton-Metre 2019-08-16 08:04 PM)

Re: Some wheely important questions about tires.

From: wheelsupport.com:

                            PCD/                      /C/B/
Mod/YR/     BOLTHOLE/  LUGSZ / ¤  /   OFF

RX8    / 04-   /5×114.3      / 12×1.5 /67.1 /   H+

On: wheel-size.com, two selected years had the same information as above

wheelsupport.com is easier to search for compatible donors at the junkyard based on bolt patterns

Re: Some wheely important questions about tires.

An Rx8 uses the common 5 on 4.5 size found on mustangs, explorers, dodges, many others.
I have a couple rx8, the oem wheels are not lightweight, at least compared to others.
I think you could get by with 17s, there are some room around the front brakes I think to fit a smaller wheel, probably lighter and cheaper.

Always a good idea to have at least a spare pair of tires and wheels ready to swap on.

Wide opinions on tires, I like the "Mayrun" brand of tires for Lemons, they need to come out with a 200tw version.  smile

Re: Some wheely important questions about tires.

We run Falken Azenis RT615K+ 245/45-17 on the fat T-bird and they grab about as well as the Drezza Star Spec II's did with half the wear.

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Re: Some wheely important questions about tires.

Has anyone run the Dunlop Direzza ZIII tires yet?  How do they wear?  They come in our car's OEM size, plus Tire Rack says they can fit a 7-inch-wide rim (of which one of our teammates has several spares), whereas the RT615K+s in 225/40 require 7.5-inch or larger.

Related question: how bad is it to try to mount a race tire on a rim that's half an inch too narrow?

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Rotaries are great, everyone should try them.

Re: Some wheely important questions about tires.

If the RS4 comes in your size, do it.

We ran the falkens on our 3400lb saab for a few years, and while they were awesome, we'd completely wear a set in a single weekend. We ran the RS4 at thompson, and we have enough tread left to run them again at NH. They have about 95% the grip of the falkens. And they're cheaper usually.


Usually you want to go wider on the wheel, not narrower. There's a ton of variables, and all tires are different, but having a tiny bit of stretch will be better than forcing a wheel that's a bit too narrow. The tire will shift around more on a wheel that's too narrow.


I think the rx8 is a 5x114.3? Shouldn't be too hard to find a set of 8" wheels and go with a 235. Facebook market is usually littered with OEM wheels for sale, I bet you could find a set that fit cheap.

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Re: Some wheely important questions about tires.

almitydave wrote:

Has anyone run the Dunlop Direzza ZIII tires yet?  How do they wear?

I have run the ZIII's and am not happy with them, we went through 2 sets at Pitt and 1 set at Thompson.  Loved the ZII's but the III's wear way to fast IMO (2,200lbs e30).  We're going to try the RS4's at NHMS and see how they wear.

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Re: Some wheely important questions about tires.

almitydave wrote:

Has anyone run the Dunlop Direzza ZIII tires yet?  How do they wear?  They come in our car's OEM size, plus Tire Rack says they can fit a 7-inch-wide rim (of which one of our teammates has several spares), whereas the RT615K+s in 225/40 require 7.5-inch or larger.

Related question: how bad is it to try to mount a race tire on a rim that's half an inch too narrow?

Skinny rims+ wide tires= squishy feel. If it is anything like mounting a 255-40-17 on a 9 in rim  you will need 2 people to mount even if you own a proper machine

10 year Dunlop fan here, we ran the dunlop direzza (1) &  (2) for the whole 10 years (aside from a couple of experimental sets ) , when it  came time to run the dunlop (3) we didn't think much and went with business as usual.... one set of 3 was run then NEVER AGAIN! Grip is good but wear like crap and are pressure finicky.

There is more, but cutting to the chase:  Congratulates Dunlop, you guys took a good endurance tire and made it into a wonderful autocross tire... Ordering our second set of Hankook RS4 now.

*rant over*

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Re: Some wheely important questions about tires.

1. RT615K+ is fine for your car. As are the ZIII. Buy whichever is cheaper.

2. 225/40 instead of 225/45 is fine. You'll likely not notice a difference. Acceleration will improve slightly.

3. I think almost all Mazda wheels are interchangable? Find some used OEM wheels from a Mazda 3 or protege or something to use as spares.

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Re: Some wheely important questions about tires.

Hey guys. This will be our third race at Gingerman. We won IOE last year with the 94 Mark VIII and finished fourth in class C (out of about 24 cars if I remember). Tires is our conversation each year..... The Lincoln has been perfectly reliable through two races. We have no go fast bits at all. We try to race consistently, carefully and race to not break stuff. Two of our drivers this year have only the two previous races as experience. A third is a rookie this year. If you’ve seen our car, you know (and have probably laughed) that we have 400TW $50 Amazon tires on the car. Four with two races and no discernable tire wear - no chunking, uneven wear etc. Two still brand new on rims as spares.  We run 2:08s consistently at Gingerman with an occasional 2:05 with no traffic. Obviously not fast, but we are always in control, have had no contact or black flags.

The discussion is before us again. We are considering the Falken Azenis RT615K+ 225/50-16 (stock tire is 225/60/16 and we have OEM wheels on the car). We can imagine downsides if we change - the all weathers are nice if it rains, they keep us honest by not overdriving, we already have them so no more money, less likely to break stuff. But, it’s so much harder for us to quantify the upside. For our 2:08 runs, how much faster could we be? We feel with our finish last year that a class c victory could be in reach with a faster car. But, maybe it pushes the judges to put us in B, which we won’t be very competitive in. Or maybe it increases the break-stuff likelihood.

Anyway, we don’t expect any perfect answers, just kind of thinking out loud. We feel like if we knew the tires could push us below 2:00, it might be fun for us to have new success by passing that barrier. It’s just hard to know if with our limited experience and big wallowing car if it’s possible just by changing the tires.

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Re: Some wheely important questions about tires.

$50 400 TW tires with no wear or chunking?

You’re not maximizing your tire, going to falkens may help simply by motivating you to push harder, but I would work on driving so you kill a set of all-seasons a weekend before getting faster tires.

I can say that the Falkens will break free more reliably and comfortably, which may give you more confidence to push faster.

But, you may as well run cheap until you start wearing the tires you have. Learn the tires break away profile and how to manage operating in that regime and you’ll both build more driving confidence as well as trim seconds.

Also if you have the air assisted suspension, drop it for a regular V8 MN-12 shock and spring setup. I learned everything about driving from MN-12s in my Teens/Twenties, that’s easily a sub 2 min gingerman car as it sits, since it has the good V8, not the crappy SOHC my T-bird did.

Work on driving first, then you’ll know when it’s time for better tires.

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Re: Some wheely important questions about tires.

Having run the Falken Azenis RT615K+ 225/50-16 and the Hankook VENTUS R-S4 225/50-16 I strongly recommend the Hankooks! They wear much better for the same money.

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Re: Some wheely important questions about tires.

You will not be bumped a class for tires alone. Going to a performance tire will help all around. Better stopping, better cornering, more predictable limits. Impossible to say how many seconds a set of tires is worth since it's largely dependent on driver, but I fully support using real tires over all seasons.

And yes, RS4 for sure. They are awesome. The falkens are a great tire, but they go away quickly on larger heavier cars. The RS4s last a lot longer.

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Re: Some wheely important questions about tires.

One point to remember about the RS4's though is that they are a directional tire which limits the ability to rotate them as much as the Falkens. That is why I went with the BFG Rival S 1.5 over them. They are however not available in 225/50R16

Re: Some wheely important questions about tires.

Hanger 18 Customs wrote:

One point to remember about the RS4's though is that they are a directional tire which limits the ability to rotate them as much as the Falkens.

From everything I know about tread patterns, admittedly I'm no tire engineer, directional tread is only relevant in wet or snowy conditions. Directional treads really don't care which direction they rotate on dry pavement.

The Falken RT615 tread is asymmetrical and isn't really any more rotatable compared to a directional tread. They still need to be mounted "This Side Out" to function in the wet.

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Re: Some wheely important questions about tires.

I'm no tire engineer, directional tread is only relevant in wet or snowy conditions. Directional treads really don't care which direction they rotate on dry pavement. .

If it helps, a partner team has a tire engineer on it and he says the same thing.

Re: Some wheely important questions about tires.

The RS4 is symmetric, so which side is the outside can be swamped (for dry racing)
but the Falkens are asymmetric and can't (for dry racing). 

Now maybe even the Falkens can be "outside" swamped, but who know how they will perform in those conditions?  anyone try it?

Re: Some wheely important questions about tires.

I've run plenty of symmetric and assymetric tires "backwards" over the years.

Never noticed any difference.  I have not tried it in the wet.

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Re: Some wheely important questions about tires.

DelinquentRacer wrote:

The Falken RT615 tread is asymmetrical and isn't really any more rotatable compared to a directional tread. They still need to be mounted "This Side Out" to function in the wet.

This is not true. With the "This Side Out" markings on the outside of both the left and right side tires, they are rotating in opposite directions from one another, unlike a tire that has a specified rotation direction, which would have the inside/outside edges of the tire swapped from one side of the vehicle to another.

The Falken is not asymmetric for water shedding reasons. The Falken uses an asymmetrical design with larger tread blocks on the outside to improve lateral grip when cornering, as the outside edge of the tire is more highly loaded in that scenario.

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