THE Wheel & Tire Thread

[Frank818]

No wonder games have a hard time simulating this stuff.

LolllllllllllllllllLL!!!!!!! That's a good one.

[Bob_n_Cincy]

Bob it is going to hit the frame. See the did you notice The how little thread in the suspension area. Jim the engineer tells how 25" will hit. I think you need 1/2 to 3/4" less dia. JMO.

I put my tires back on tonight to check clearance.
As I stated in post #118 my fronts are going to be Toyo Proxes R888 225/45ZR16 55 offset rims. They are 23.8 inflated diameter. They are at 41 psi right now.
I have about 1.25-1.5" on the right and 1.0 to 1.25 on the left.
see attached pictures.
right clearance.jpg
now the left side
left clearance.jpg
the 245 front tires Michael wants to use sitting next to a stock impreza tire
wide.jpg
Sébastien Loeb tires
Sébastien Loeb .jpgSébastien Loeb2 .jpg

[wallace18]

I put my tires back on tonight to check clearance.
As I stated in post #118 my fronts are going to be Toyo Proxes R888 225/45ZR16 55 offset rims. They are 23.8 inflated diameter. They are at 41 psi right now.
I have about 1.25-1.5" on the right and 1.0 to 1.25 on the left.
see attached pictures.
right clearance.jpg
now the left side
left clearance.jpg
the 245 front tires Michael wants to use sitting next to a stock impreza tire
wide.jpg
Sébastien Loeb tires
Sébastien Loeb .jpgSébastien Loeb2 .jpg

I stand corrected! LOL.

[EricScottZehnder]

Am I right in thinking that you need to add more positive offset for the larger tires because the tire needs to sit deeper to the center of the car body to not protrude out the side of the fenders? If so, how large of a rear tire can you use? There has to be some absolute limit like 315, 335 or something (even though I would never consider such wide wheels on a car this light).

[Bob_n_Cincy]

Am I right in thinking that you need to add more positive offset for the larger tires because the tire needs to sit deeper to the center of the car body to not protrude out the side of the fenders? If so, how large of a rear tire can you use? There has to be some absolute limit like 315, 335 or something (even though I would never consider such wide wheels on a car this light).

The back wheels are limited inside by the upper and lower trailing arms. FFR is saying 255 max with 40 offset rims.

[EricScottZehnder]

Bob - If 255 is the max rear than aren't you worried about having an oversteery mess with 245 fronts? It sounds like Wayne believes 30mm split would be best which is 225 fronts.

[Bob_n_Cincy]

Bob - If 255 is the max rear than aren't you worried about having an oversteery mess with 245 fronts? It sounds like Wayne believes 30mm split would be best which is 225 fronts.

Sorry if I was confusing.
Only my son wants to run 245 on the front. He is 16 and also wants 800 HP.
I plan to run 245/45ZR16 for the rears and 225/45ZR16 on the fronts.

As a side note: I have a 400 lbs battery pack I could put in the same box as the master cylinder giving the car a 50/50 weight. If I do this, I may run a square set of tires.
Bob

[WRX Dave]

Using the shorter wagon rear control arms, would it work to run a 30 offset and open up more clearance for a wider rear wheel?

[Bob_n_Cincy]

Using the shorter wagon rear control arms, would it work to run a 30 offset and open up more clearance for a wider rear wheel?

Hi Dave
I started out running my shorter wagon arms with my stock 55 offset wagon 6 1/2" wheels.
Only have 1/2" clearance between upper and lower trailing links and tire.( I am running 9" wide 225 tires on 6 1/2 rims)
If i went to 30 offset it would move the wheel out 25mm (1") so you could go to 11" 275 tires.
Note ( my side walls don't bow out because of narrow rim. If you put 275 tires on and wide rims, your overall tire width will be greater than 11" and might rub)
I think Wayne is doing some extra curved trailing arms to help with this.

I don't want to go to real wide tires but I do want them flush to the side of the car. So I put in adj. lateral links and set them to sedan width and then some. I'll set my rear quarter panels in place this week to see how the look.

Another note: I like the big offsets (55) because it keeps the bearing in the center of the tire.

Bob

[WRX Dave]

I wouldn't be worried about the rear wheel bearings on this car. They haven't worn out after 150k miles on my '03 WRX, and that includes about 25 hours of track time and six years of rallycross abuse. Given the weight of the 818 we should be able to run any offset that fits under the fender without bearing issues. The fronts are a little more of an issue. I had to replace both fronts on mine before 75k miles, and my friend who tracks his '05 on R-comps has gone through five front wheel bearings in the last two years. The more serious Subie guys I know keep a spare set of assembled front uprights in their race trailers.


I'm not planning on anything that crazy with rear wheels. Probably just a 17x9 or 18x9.5. There seem to be a lot more wide wheel options at 30 than 40 offset, so my plan would be to run 30 offset with wagon arms in the back with 245 tires, then use 17x8 wheels in the 40-48 offset range up front on sedan control arms with 215 tires.

[Mechie3]

Posted these in my build thread too.

225/40/r18 on an 18x8 et 48 wheel. Random wheel/tire I had lying around to make a table out of. Maybe 1/8" of clearance at the firewall. Plenty of clearance at the strut and upper ball joint. Math says diameter is 25.09". Tire was a Bridgestone RE 760 sport.




225/45/r17 on a 17x7 et 42 wheel. These are my WRX winter wheels. It only cleared the firewall because a groove in the tread lined up perfectly. A slick at this size would rub slightly at full lock. Math says diameter is 24.97. Tires were Blizzak WS-60

[mrprgrmr]

Reading this thread, I am trying to decide if there is any tire configuration that would be safe for use with my stock wheels (16 x 6.5"). For the moment, lets assume there is someone out there (me?) who would rather not spend $1200 on wheels at the start and would prefer to run on stock rims. Tires wear out and the wheels could be upgraded later.

The goals would be:
1) adequate traction for typical street conditions - spirited but not insane driving
2) Minimize the chances of oversteer & spinning the car due to inexperience and MR design
3) Ignore aesthetics for the moment
4) Ignore "ideal" and think about "adequate"

Assumptions:
1) The maximum width tire on a 6.5" wheel is 225 (yes, it would be a bit bulgy)
2) The minimum width tire on a 6.5" wheel is 190
3) The "ideal" configuration suggested by FFR for an 818S is 215 front and 255 rear (it's in the assembly manual)
4) 818S with a stock WRX power plant (round down to 225HP - it's an old engine)
5) FFR designed the 818 to handle more than stock HP (perhaps 300 HP?)

#4 is the only one I have absolutely no evidence for - it just seems to make sense. If you were to downsize the front tires to 190 and plus size the rear tires to 225, you would have 35mm difference between the two. Perhaps a little less because of non-ideal rim size for the 225's. I think you would have roughly 12% (25mm) less contact area in the front and 12% less contact area in the back compared to FFR's stated ideal 215/255 combo, with 25% less power (225 vs 300 HP design assumption). It might be butt ugly but this seems like a reasonable combo to attempt from a performance/safety standpoint. I would tend to think you could improve the appearance a little playing with the sidewall sizes.

Is my logic seriously flawed or should I just resign myself to the implausibility of building this car with stock wheels.

[Xusia]

Like you, I spent a lot of time worrying about these issues, along with fitment. I was in a slightly different position, as the wheels on my donor were for, all intents and purposes, destroyed in the crash that made it a donor. I had to buy wheels, whereas you don't.

You stated you want to use the stock wheels, but that seems mostly based on the perceived price of new wheels. After doing all my research I think using the stock wheel is going to be a compromise, and new wheels can be had for less than you might think. Specifically, I would suggest looking into the XXR line of wheels. They are very affordable, are not bad in regards to weight, and allow fitment of tires much more suited to your intended use. I bought a set of the XXR 530 (17x7 ET+35 front, 18x8.75 ET+33 rear) for less than $500. And that included shipping.

Bottom line is it's both an easier and better solution. Yes, you'll spend some additional money up front, BUT:
1. Think of it as insurance (better traction means less chance of an accident)
2. You'll spend less time thinking/worrying/dealing with this

[mrprgrmr]

Xusia - Thanks for setting me straight. You found the one assumption that I didn't explicitly state as such (and was wrong). Somewhere in here, I was seeing posts listing $300 each as reasonably priced wheels so I assumed roughly $1200 unless I went with steel wheels (not necessarily a bad idea if I could find them). Obviously, we all have different expectations and I don't see $300 each as unreasonable for good quality wheels but it is more than I wanted to spend considering I basically like the Subie wheels.

For $500, I agree that it is not worth taking chances with an untested and inferior combination. Sooner or later, the Subaru wheels may go on eBay or craigslist so I can recoup some of what I spend on new wheels.

XXR FTW!

[Xusia]

Did I mention Wayne is an XXR dealer?

[SixStar]

Remember that "fit" is a relative term.

I run a 17x9 on my WRX with a 275/40-17. Rolled rear quarters and the front liners need replacing frequently, but that's the price to pay for a Solo championship.

Here's a 18x10.5 with 295s (closer to 305, silly Hoosier) on the 818R.

ujjWpJa.jpg

[bnr32jason]

Not trying to spam this, but I just lowered the prices on my wheels for sale (by A LOT):

http://thefactoryfiveforum.com/showt...s-(818-Fitment)

Not building my 818 as hoped, so need to get these sold so I can start my other project.

[Scargo]

I've been saving up a lot of thoughts for this moment (having read all this in one sitting). Probably can't remember them all.
It would be nice to see any notation of wheel clearance and setup in the spreadsheet. Some might run a different rear spring diameter, for instance.

I can see that a lot of people will not be wanting to see how big they can go. The Prius tire size example reminded me of how I would not have been able to drift my Prius had the tires been bigger. Also, and especially with a light car, hydroplaning can be a real problem when the tires are too big.

I don't think a Pike's Peak dirt tire and it's profile is applicable to a hard pavement race tire.

My 275x35x18 BFG's are 25.5" tall. They are the equivalent of a 285 Hoosier. Am I correct in my impression that in the rear, they are too tall and will rub up top and in front?
255x40x18's with 40ET are being run on the rear of the FFR car. What rim width and offset? What about a 45 or 48 offset wheel in 10-10.5 width? Has anyone tried either?

Some 17" wheels will not work with a 282 mm BBK and some BBKs fit more easily than others. I'm still puzzling over how big a BBK to go with on the front and how it might affect my wheel choices.

[Xusia]

I don't have my body on yet, but I think you are going to have a hard time fitting anything that is 285mm wide (I don't understand why they would label it a 275 if it has a 285 section width, but that's another matter). With the right wheels & trailing arms you can get a 265 in the rear. You might also check Erik Treve's thread. I know he is running some wide tires.

In the front, good luck. Lots of issues. If you don't want it rub, tire sizes are limited.

All that said, general wisdom says wider is better, but on the other hand, FFR's 818R is putting down blazing lap times, and getting awesome corning and braking forces. All on smaller tires. Just sayin...

[Scargo]

No, your points are well taken. With the FFR racer, that was with around 300 WHP or about 7:1. I am building for ST1 or 5.5:1. As an aside, I've been told STR is being eliminated and I don't know how they ran the car in STR-3, which has a 9:1 power to weight limit.
My intentions are to build a completely unique front suspension so all the mounting points may change. The wheel center point may move forward and out, especially if I lengthen the LCA. I'm just speculating since I have no dimensions and no kit. No kit means I am on here, spouting off more.

[Santiago]

I'm pretty sure that they first ran the Blue R-car in STR-3 with a different turbo on the car. Put differently, I think they were legal then, but didn't bother to remove the class designation for other events in which that class wasn't being run. I think now they would be in ST1 with the same 300-320whp. You've seen my calcs on the classing. I think with most of the weight targets folks will have, we're looking at similar power levels if we also run slicks like the R-car does.

I'm also planning something different for the front - not quite a "unique" front suspension, but working with what we've got within reason (although I'm not sure others would share my standard of reason). I'm not so much interested in fitting wider tires as much as getting wider track. Dave Smith is fond of saying "weight is the enemy" and he's right...but I think it's more helpful to think in terms of saying "weight transfer is the enemy." A necessary evil (like weight), but an evil all the same. I think I'm going to start using that as my tag line...

Anyway, if you're going to revamp the front suspension, do what you can to increase track (and plan on being able to do similar in the rear). Bottom line: we're flaring those fenders buddy! They got to go.

Oh, on the BBK concerns, some of the more track-oriented vendors will work with you using templates to confirm wheel fitment. So if you've got a BBK in mind, see if you can find a wheel vendor who's willing to use it before you buy. I know of some who've done this for me in the past, but they're not on these forums so contact me direct. I wouldn't be surprised at all if Wayne would check a template for you if you're looking at some of the wheels he sells.

Best,
-j

[Scargo]

Traction! We need to generate more traction! My new byline...

"We're flaring those fenders buddy! They got to go."
I'm on board! She needs to have more of a "big butt" look! We're dealing with raw bodywork. Slap a curved piece of material on there and start laying up against it! No biggie.

[bompus]

Can you add these tires to your shared Google spreadsheet?

Sumitomo HTR Z III
- Cost 146 , Weight 26 lbs , Rim Size 18 , Rim Widths 8.5 - 10 , Tire Size 255/35 , Section Width 257mm

Sumitomo HTR Z II
- Cost 76 , Weight 20 lbs, Rim Size 17, Rim Widths 7 - 8.5 , Tire Size 215/40, Section Width 216mm

Now a wheel question... I'm planning XXR 530 18x8.75 +33 rear with 255/35 , 17x7 +35 front with 215/40 - does anybody see any issues with this and the stock setup?

[Wayne Presley]

Can you add these tires to your shared Google spreadsheet?

Sumitomo HTR Z III
- Cost 146 , Weight 26 lbs , Rim Size 18 , Rim Widths 8.5 - 10 , Tire Size 255/35 , Section Width 257mm

Sumitomo HTR Z II
- Cost 76 , Weight 20 lbs, Rim Size 17, Rim Widths 7 - 8.5 , Tire Size 215/40, Section Width 216mm

Now a wheel question... I'm planning XXR 530 18x8.75 +33 rear with 255/35 , 17x7 +35 front with 215/40 - does anybody see any issues with this and the stock setup?

Wheels will work well but you may want a stickier tire than those on such a light car.

[Xusia]

EDIT: Spreadsheet updated.

As for fitment, you shouldn't have any issues with those sizes. I have the XXR 530s in those same sizes, and I'm running the same tire sizes (different brand; more on that in a sec). They are good match for the car.

As for the tires, I have no experience with the HTR, but you might want to consider the Federal 595 RS-R. It's [supposedly] very sticky, and a bit cheaper for a set. They do tend to run wider than their indicated size, but they still fit those rims very well and have no clearance issues.

Here are 2 views the fitment of the tire to the wheel:
IMAG0558.jpg

IMAG0559.jpg

I don't have any pics of the back wheel & tire, but fitment is idential.

[bompus]

I like the Federal 595 RS-R .. they do seem harder to find, but not impossible. I was somewhat concerned in using a soft tire because of how hot it gets in Tucson, AZ ( hot! ) that the softer tires wouldn't last very long. I guess I can always give them a shot and see how they perform. Thanks for the quick responses guys.

[C.Plavan]

Bringing this thread back to life- I'm getting ready to pull the trigger on some race tires for the 818R. I need some opinions. Please note: I have 5mm and 3mm spacers to adjust fitment.

Hoosier R6's

Front- 225/40 R17 on a 17x8 inch rim +38 (23.8 diameter, overall width 9.8, tread width 8.9) Spec measurements were on a 7.5" rim
Rear- 255/45 R7 on 17x9 inch rim +40 (26.2 diameter, overall width 10.8, tread width 9.8) Spec measurements were on a 9" rim

Toyo RR (new race tire)

Front-235/40 R17 on the 17x8 +38 rim (24.4 diameter, overall width 9.5 -no tread width listed ) Spec measurements were on a 8.5" wheel
Rear- 275/40 R17 on th 17x9 +40 rim (25.7 diameter, overall width 10.9- no tread width listed) Spec measurements were on a 9.5" wheel

Optional Rear- 255/40 R17 (25.00, 10.2) Spec measurements on a 9.0" rim

So there it is. My dilemma- I don't want to buy $ tires and say $&*^. What does the 818 "Think Tank" think?

[Santiago]

Not sure what sort of "thinks" from the tank you were interested in, so I'll just try a stab at some random thoughts.

Fitment: looks like all o.d.'s should fit fine, so you're clear there.

Tire options: I'd lean towards R6's just because I'm familiar with the tire (it's my choice for the first "test tire"). I thought (don't quote me on this) that the RR was a step down from the R6 in terms of overall grip. If so, another reason to opt for the R6, unless longevity is high on your priority list.

Height Differences: obviously the R6 combo you spec'd out has greater fr/rr size difference. You're looking at a noticeably taller sidewall in back, but honestly I don't know what to tell you about that for our application. In theory you might expect the front to have a crisper response than the rear, so maybe you would end up looking at working to tune that difference out if it surfaces in a nasty lag between the time it takes for the front and rear to take a set. I dunno though...shooting from the hip here...

Stagger: I have to say I kind of like the idea of a 40mm split. I know Wayne has spoken fondly of the 30mm split that the Blue R-car ran, but I think that was with the front sway bar in play. I'd like to take that thing off and work with springs/tires/track to balance the car out. So removing the front bar might make your "wide" rears a sensible route to get the rear to come up to par with the increased front grip.

All in theory of course.
You're just one of the lucky chums who gets to do the concept validations.

Best,
-j

[Wayne Presley]

the 818R that I drove didn't have a front bar

[Rasmus]

I'm getting ready to pull the trigger on some race tires for the 818R. I need some opinions.

What's your primary use going to be? AutoX? Track Day? Drag Race? Time Trial? Hill Climb? 24 hr endurance? Rally? MotoGP?

[Santiago]

the 818R that I drove didn't have a front bar

Wayne, did you drive it with the Hoosier R6's or the Yokohama Advan A005 slicks? Just curious.

What I'd really like to know is what their tire temps looked like... =) I have this worry (probably unfounded) that we might have trouble getting a larger tire up to temp in the 818 (and just as a heads up, fender flares are a given for me, so when I think "larger" I'm not constrained by that for how large).

Chad, along the lines of Rasmus' question, are you planning to compete in a class that you can fit into with 275s? Are the 255s going to permit you more legal power for your class? I guess, I'm asking if we should also be contemplating the trade offs between tire size and legal power?

Best,
-j

[C.Plavan]

Wayne, did you drive it with the Hoosier R6's or the Yokohama Advan A005 slicks? Just curious.

What I'd really like to know is what their tire temps looked like... =) I have this worry (probably unfounded) that we might have trouble getting a larger tire up to temp in the 818 (and just as a heads up, fender flares are a given for me, so when I think "larger" I'm not constrained by that for how large).

Chad, along the lines of Rasmus' question, are you planning to compete in a class that you can fit into with 275s? Are the 255s going to permit you more legal power for your class? I guess, I'm asking if we should also be contemplating the trade offs between tire size and legal power?

Best,
-j

Strickly road racing- I am familiar with the R6's also- But the new Toyo's are cheaper (test tire), and stick/last longer than the Hoosier. Plus the Toyo's have a better contingency program.

I will be racing with NASA, At first I am not worried about the classing/tire size. I just want to make sure the car is reliable and work the gremlins out. Then I will worry about what class I will fall into.

I'm really interested in the Toyo's and want to test them out. I would hate to flat spot the pricer Hoosier adjusting the brake bias the first time out!

I just wanted to see if the sizes listed above are even doable. Keep in mind the Hoosiers are much wider than other tires of the same size.

[Santiago]

Keep in mind the Hoosiers are much wider than other tires of the same size.

No! Hoosier wouldn't do that...

Ok, so the RR's sound like they make sense for your gremlin runs. Are you flaring fenders? If not, you may be on the wide side. In front, Erik T. tried 235s but I think they were of a much larger outside diameter.

For the back, things might get dicey. The Road & Track article featured the Blue R at Gingerman wearing Hoosier R6s (if I'm not mistaken). I'm not sure exactly what size they were, but maybe Wayne knows. Here's a look at them:

ROA070113FEA_KITCAR_3.R1.p1-sm.jpg

Looks like that sets your limit on what will fit, unless something like Wayne's trailing arms would allow you to tuck this in further than what you see here. I also don't have any specs on what wheels were on the Blue R for this pic.

Best,
-j

[Rasmus]

Strickly road racing

American Racing makes several nice all-stickys.

Look at that tread pattern! That's the "I-mean-business-super-cereal" pattern. They even make them 16 different grades of softness/stickiness:

User review on the GRM forums.

Largest wheel diameter they make tires for is 15". I'm looking at their 23.5-10-R15's for AutoX which in metric is about a 275/40R15. Sticky steam rollers.

A metric 275/40R17 in an old-skool imperial size 15" would be about a 25.5-10-R15 or a 26.0-10-R15

[Scargo]

Per Jim Schenck, "wheels on the R are Rota Torque, the rear are 18x9.5 with a 35mm offset and they do rub slightly with the 255 hoosiers although those tires have a section width more like a 275 than a 255". He also said, "The tires rubbed on the outside, but there were two other factors that kind of cancle each other out a little. The R sits about an inch lower which hurts clearance but we ran more static camber which helps it. A slightly narrower tire like the 255 Toyo, and 5mm more offset is what we have on the white car and it is a nice fit. Maybe a 275 could be made to fit with some specific brand and just the right offset but I think it would probably require a bit more camber than you would usually run on the street, so we are saying 255 is max for what we know will work without problems."

As to tires, I was pleased with the traction, life and price of the Goodrich R1-S. I made this switch kinda late in the season, when things were cooling down on the track. I've gotten good life out of them. They say they are not as well suited for extremely hot days.
This was after running 888's and just previous to the BFG's, Hoosier R6's.
A 17" 255-40 R1-S (10.3"TW/10.2"SW 24.8"D) will run you $265 from Phil's, while a R6 255-45(9.7"TW/10.8"SW/26.2"D) will run $288 and a .010" shy of 4/32" tread depth Toyo RR is 10.2"overall width and 25"D for $232 (the cheapest). The BFG and Toyo look interesting if for nothing more than the footprint, sidewall width and smaller diameter. Did not see Toyo listing tread width.

[07FIREBLADE]

What are the fronts for the 818R, i know the rears are rota torque 18x9.5, just need to figure out the front size.

[Wayne Presley]

Wayne, did you drive it with the Hoosier R6's or the Yokohama Advan A005 slicks?
Best,
-j

I drove it with the R6's


ROA070113FEA_KITCAR_3.R1.p1-sm.jpg

Looks like that sets your limit on what will fit, unless something like Wayne's trailing arms would allow you to tuck this in further than what you see here. I also don't have any specs on what wheels were on the Blue R for this pic.

Best,
-j[/QUOTE]

The arms do allow you to tuck more tire under the body

[wleehendrick]

I've been debating what wheel/tire size to run on my 818S. To avoid rubbing issues in front, a OD (overall diameter) of less than the Subaru stock 25" seems to be recommended. The issue is, with a 17" wheel, this really limits tire choices wider than 205mm. There is very limited choices in a 215/40-17, but almost nothing >225mm.

So, what about a 16" rim in front? I'm really not up on what will fit, but this occurred to me when I noticed that the donut (space saver spare) from my donor is 16". I've got 2006 WRX brakes, and the knew that stock alloys were 17", so I had only really been considering >17" wheels and tires. But since the spare is 16", 16x7 or 16x8 rims should clear the brakes in front... Is this a correct assumption?

I'm not hung up on big rims... and this opens up a lot more choices for sticky rubber in the front in 225/45-16. I'm thinking a 255/40-17 in the rear which would provide a nice staggered set-up. The 30mm width difference seems to be recommended for balance, and aesthetically, I think the same sidewall height with a 1" larger rear wheel will look best.

Thoughts?

[Bob_n_Cincy]

I'm not hung up on big rims... and this opens up a lot more choices for sticky rubber in the front in 225/45-16. I'm thinking a 255/40-17 in the rear which would provide a nice staggered set-up. The 30mm width difference seems to be recommended for balance, and aesthetically, I think the same sidewall height with a 1" larger rear wheel will look best.

Thoughts?

These are 225/45-16 R888 on 16x6.5 55 offset stock rims (Last years G-Stock autocross wheels)

P1040667s.jpg

P1040661s.jpg

[wleehendrick]

These are 225/45-16 R888 on 16x6.5 55 offset stock rims (Last years G-Stock autocross wheels)

R888's are what I'm thinking of, that size in front. On a 17" front rim, R888's would require dropping to 205's, or possibly rubbing with a 215-225/45-17. I see you have th 02-05 brakes. My donut is 16" and Tirerack shows 16" ('-1') wheel fitment for the 06 WRX, so I'm hoping there's no clearance issues with the 4-pots, just want to hear from someone that's tried it.