Would 23 lb wheels (Miro) offset the advantages of upgrading to grippier tires?
 

I'm currently driving stock wheels/tires and I keep hearing that upgrading to grippier tires such as Pilot Super Sports will transform the car into a handling dream. I'm about to purchase a set of Miro 398's 18x8.5 (TE37 reps) with 225(or 235)/40/18 PSS tires all around (square).

For street driving will the handling characteristics between the Miros and a wheel such as the RPF1 be very noticeable? I don't want to cancel out the handling advantages by equipping wheels that are too heavy. Also, would you guys recommend 225/40/18 over 235/40/18? Thanks!

Im going to guess your acceleration will be effected, noticably. Where as lateral grip may be improved. Either way I like the RPF1>TE37 style.

I wouldn't worry much about a few pounds extra for wheels unless you're being paid for your lap times...

It's a personal thing, but increasing or reducing unsprung weight will not only impact acceleration times, but how your suspension reacts (ie there's less or more weight for the suspension to try and keep in contact with the road). I run significantly lighter wheels (Desmond Regamasters) on my car, and I find the difference in ride and handling more noticeable than any difference in acceleration.

A change in unsprung weight does not "offset" an increase in grip; at least not directly.

If it did have a measurable effect, you would have bigger issues to deal with, a severely underdamped system, to be precise.

I run those wheels: Miro 398's 18 x 8.5 with 245/35/18 pilot super sports. That tire size keeps the gearing the same as stock 215/45/17. Grip is improved to the point where I can't psychologically drive fast enough on back roads to find the limit (I don't feel safe/within my skill level driving that fast basically). According to the quarter mile I'm about even maybe a little slower not sure yet and I haven't ran it enough times in the cold weather.

However, on the street its not noticeable really. I have the standard bolts-ons and e85 ecutek tune. The weight difference is only 3-4 lbs anyways.

Edit: Miro's 22 lbs My PSS tires: 22 lbs
stock wheels 20 lb , stock tires 20 lbs.

Hmm the difference in acceleration, if any, is not noticeable to you during street driving? My motor is stock so I'm not sure if the same would apply to me. What would be the advantage to retaining the stock gear ratios? Gas mileage? Also, what kind of drop did you do?

Ok, I'm going to speak with experience since overall my rim + tyre package I'm running is slightly heavier than stock.

I'm running Advan RG-D 18x8.5 and they're 17.6lbs which are much lighter than the 23lbs you mentioned. Add tyres to the rims and you have something heavier than stock. It's never just the weight of the rim but how big (17 or 18) and wide rim you're going. It's also the weight of the tyre added to it and if you're running wider, you need wider tyres and that's more weight.

With my RG-Ds and Kumho KU39s(235/40/18) and stock motor, I feel a difference in a lot of things. It takes more gas to get it moving, it takes longer to stop and it doesn't feel as direct in terms of steering compared to when I was stock. I've gone back and forth between the RG-Ds and stock rims enough times to give you my 2c on this.

For our cars, I advise against heavy rims period. If you only care about aesthetics and don't care about how it drives then by all means do whatever. But if you do, go lighter and think about how much the tyres weigh too. If you insist on getting those rims, invest in a decent set of coilovers and some kind of tune eg. OFT. It'll offset the weight and you get more out of the setup with coilovers than stock suspension (get's rid of that sluggish steering feel and bumps up the grip).

Anyway that's my 2c.

Hm, based off what I'm hearing I'm leaning toward lighter wheels. Any budget friendly suggestions, maybe XXR 527/530? Also, would springs (1 inch drop) instead of coilovers suffice?

XXR are heavy.

Budget friendly rims I'd rims I'd suggest would be 17x8 Enkei RPF1 or 17x8 Wedssport TC105N with decent performance tyre of choice. With these you can go for springs and it'll be pretty awesome. Checkout F1point4's build. He's got lowering springs and 17x9 TC105N. It poked a bit without camber adjustment and iirc he's got camber bolts up front and adjustable LCAs in the rear. Also, he rims + tyres weight a touch over stock but only a slight bit.

If you end up getting slightly heavy rims, springs wouldn't make you happy. It'll improve the handling a bit but you'll want to go for (at least two-way) coilovers to adjust the dampers to improve steering response and handling to where you want it.

Right acceleration is not noticeably slower at all. Yes stock ratios will give you better gas mileage because the cruise rpm is lower. I have Hotchkis springs so 20-25mm drop. Not much because I dont want to deal with camber adjustment parts and scraping speed bumps, driveways, etc.

Like the others are eluding to you need to get big brand name wheels to go lighter. The Miro's are low pressure cast which is the typical OEM process so no issues in strength just 2lbs heavier.

I considered looks as well as performance. There certainly is subjectivity or personal preference to appearance as well as performance enhancing qualities when choosing a tire and wheel combo.I went with a 16” Weds SA15R because I thought it was a good looking wheel and light.These wheels weigh around 14.6 lbs. The tires you are looking at the Michilen Pilot SS weigh 22lbs for the 225/40/18 and the 235/40/18 weighs 23lbs. Also the tire in this size is larger than stock which the 225/40/18 is 25.1” and the 235/40/18 is 25.4” So if the wheel weighs 23lbs and the tires 22 -23lbs we are looking at 45-46lbs per wheel per corner. If you went with a good street tire like a Continental Extreme Contact DW a max performance summer tire, which is a more comfortable and better handling tire than stock in either a 205/55/16 (at 19lbs) or a 225/50/16 (at 21lbs) If you considered the 16” option in either a, Weds, enkei rim, volk te37 11.??lbs , or a TWS t66f at (10.8lbs per wheel or so) you would be(w continental DW225/50/16 and a Weds SA15R) per wheel at 35.8lbs with a height of 24.9.or with a maximum lightness of a 205/55/16 Continental Extreme Contact DW (weight is 19lbs and height 24.9) and the 16x7 TWS (10.8lbs) you would weigh in at 29.8lbs per corner .So if you went with the TWS at around $600 per wheel and a 100$ Continental tire the 205/55/16 you would be a maximum of 16.2lbs lighter per corner.You would save a total of 64.8 lbs and the tire would be shorter in height and with a shorter height you will gain faster acceleration.This combo of the tws 16x7 wheel and the 205/55/16 tire should cost around 720 or so total.This is one of the lightest combos I know of.For a street car you would be just fine and probably more comfortable too with the softer sidewall of the 16” as appose to a 40 series.Anwyays you can’t go wrong there is subjectivity here, looks vs, performance. Vs cost.

Exactly why I went to a PSS in 245/35/18 its diameter is 24.7 and 22lbs. Remember the Miro's are 600-800/set of 4. Just depends how much that less weight means to you vs. expensive wheels. The savings on wheels could get you halfway to FI then a couple pounds of wheel weight don't matter much. Depends if you just daily or track. I autocross but just for fun.

Thanks! Some good points!

I didn't read the whole thread but I feel better traction is more important than the slight weight increase per wheel. If you can pick a lighter wheel, great but if you are choosing stock tire/light rim or sticky tire/stock rim and looks aren't a factor, then sticky tire wins.

The extra weight is not THAT big of a deal. More traction will let you maintain speed and launch harder. You'll just spin those stock tires anyways so the weight/acceleration difference is negligible

The difference is that it's not just weight, it's unsprung weight, and not only that, it is rotating weight as well. Pound for pound the most effective weight loss.

So the reason unsprung mass is so important is that it is what pushes against the car over bumps. When the tires see a bump, it's the tire and unsprung mass that sees it. less unsprung mass basically follows bumps better, transmits less road bumps to the car, and lets the car push it down better onto the road. All in all, more traction, and more comfort! (as a side benefit, it decreases the spring rate you need by a linear %, ie a 10% reduction in mass means you need 10% less spring, which is a good thing)

Then the rotational mass thing, is it takes energy to spin it up and stop again when you are accelerating and braking, so less rotating mass lets you accelerate faster and saves your brakes.

To the op's question... I have no idea, haha. They kind of gain and lose performance by completely different means.

In any event, if you care about performance, why not both? get light weight 16" and enjoy your performance and you save money in the long run with cheaper tires. The era of needing low profile tires is over. modern tires are good.

I understand how sprung and unsprung weight works. But unless you're a super serious racer(op mentioned street use I believe), you won't notice it. The extra traction will be far more useful

I'm not a huge purist when it comes to weight savings and I have no intention of tracking the car, just spirited canyon drives and daily commutes. I mainly care about retaining the handling, throttle response and acceleration of the stock set-up, and if possible, improving upon the handling/grip aspects. Because of this, I'll avoid any wheel over 17/18 lb.

I also care about filling the wheel gap to some extent, and the aesthetics of the wheel. I'm leaning toward a 17 inch wheel for the reasons mentioned in this thread, but I'm not too sold on the appearance of the rpf-1. I wish there were some lighter weight wheel options for less than $1200/set that looked similar to the TE37s or even the XXR 527s.

Personally I am saving for the 17" tws motor sports t66.
IMO they look awesome, so tick the aesthetics box.
They accommodate certain bbk's. Another tick.
They're also quite light. So tick the performance box / light weight box.
17" tyres shouldn't be too expensive either. (Compared to 18/19s anyway!). So tick the 'ongoing costs' box too.

Downside is that they ain't cheap! Hence the need to save!
But the way I see it is that if I am going to spend cash changing the wheels (or anything else) I'd rather wait a little longer and do it properly. It'll obviously cost more, but I'll maximize my satisfaction rather than always wondering if I should've gone 1 better.


Now to tick the bank manager box ;-)
:grin:

Look at what tires you want ahead of time. A lot of tires don't come in 17s any more or only in limited widths. Usually these tires cost more than the 18s because of the smaller production runs

Thanks for the tip. We seem to be ok with 17s here though I haven't checked in depth. Will do some calling in the new year!

Where did you get 23lbs from? I just ordered a set of Miro 398's from NLmotoring, and they have them set at 21.7lbs a wheel

IMHO, it's hard to beat the Enkei RPF1's for the weight reduction and cost per wheel. I am running PF01s which aren't quite as light but I preferred the looks.

Some other considerations:

I would recommend staying with a 17 inch wheel going wider than stock. Remember smaller diameter wheel in the same model will save weight as well; additionally the smaller diameter tire will save some weight relatively. If you lower with springs or coilovers, the 17's look great in my opinion.

In my experience, I went to a 7.5 inch width and put 225's on them and am running Super sports. The grip and ride quality were dramatically improved; I also felt the car accelerated and stopped much better than stock as well.

It is all personal preference, but...

Unsprung weight and tire sidewall stiffness have a big effect on ride and traction. Sidewall height and stiffness affect steering feel. If you drive on real roads (i.e. bumpy) and don't track the car then I recommend sticking with a 17" diameter. Reducing sidewall height 1/2" by going to 18" will make the steering feel sharper but will significantly reduce ride quality and traction, in the corners and on the straights. It will also be significantly more expensive to find a light weight 18" rim vs a 17". Going down to 16" is a bit extreme unless your roads are really bumpy. I seriously considered it, but wasn't willing to risk a reduction in steering feel from the increased sidewall height.

There are some decent looking, modestly priced, light weight 17" rims out there. RPF1s are ubiquitous. I also looked at the Kosei K4R, but in the end I chose 17x8+35 720Form GTF1s (15.5 lb) with 225/45R17 Michelin PSS, which is an awesome tire, with a great balance of weight, cost, street performance (dry/wet traction, steering feel) and longevity. That combination ends up ~3 lb per corner less than stock. The Conti ExtremeContact are potentially ~ 1 lb lighter again but are reputed to have a bit less dry and wet traction and less steering feel than the MPSS.

The extra 8mm (~1.4%) diameter of the 225/45 MPSS over stock isn't noticeable to me. The much wider contact patch, stiffer sidewalls, stickier rubber and tread design are vastly better than stock, with better dry and wet traction. They are also much noisier than stock. Steering is heavier but with more feel. The ride is interesting. With stiffer sidewalls but lower unsprung weight, I notice sharp edged bumps a bit more but general rough pavement doesn't feel worse than stock. The MPSS suck in the cold, but in LA that shouldn't be a problem.

Back in the day, I had a base Integra RS that came with 14" steel rims. I got a great deal on a set of 17" rims and 205/40 tires. I wasn't really thinking about unsprung mass at the time but I sure learned. It was a bit of an extreme case, but the ride was terrible and the additional grip disappeared when the road wasn't perfect. I've been a bit circumspect about tire and wheel choices since then.

Good luck with your decision.

I got 23 lb from calling the Miro customer support line listed on their website. For all I know, the guy I spoke with could've been mistaken.

Thanks for the info! I've just about settled on the RPF1s after browsing some member photo galleries. I would get 17x9 (for flatter face) + 35 offset with a 1 inch drop on Eibach proline springs. I also hear I should dial in some negative camber to diminish some of the poke with a +35 offset. For tires I'll get PSS 245/40/17. Does this sound like a good overall set-up?

Also, would I need to get camber bolts to dial in negative camber, and can anybody chime in on some good camber specs for the above set up? Thanks.

Sorry, dude. You're getting well outside my experience. There is lots of info on wheel and tire fitment in the forums, so search away. A quick look at the Wheel Fitment thread (http://www.ft86club.com/forums/showthread.php?t=7535) shows +35 on 9" wide wheels with a 1" drop probably pokes too much, so camber could help prevent rubbing. More positive offset would help that situation - 17x9 RPF1s are available in a +45. That's much closer to the OEM offset, so will have a smaller impact on steering feel. (I would have gotten rims with +45 offset if I could have at the same size, weight, cost, etc).

Like I said before, its all personal preference. You have to ask yourself what you want to get out of the car. For my tastes, 245 wide MPSS would be too much tire on a street driven Twin with stock power.

Thanks! What do you mean by "smaller impact on steering feel?" +45 would retain the lightness of the stock steering feel?

Steering feel is complex and I'm no expert, but... Going from the low grip OEM 215 section tires to higher grip, wider tires is going to increase steering effort but not necessarily the feel. You'll notice the increased effort especially at parking lot speeds.

Moving the center of the contact patch outward by 13mm vs 3mm (stock is +48) will have its own effect, but it won't be large. There is precious little info on the Web about the effects of increasing scrub radius, independent of other geometry changes (caster, camber), but what little there is seems to indicate that the effects are minimal until you get to big positive or negative numbers. Back in the bad old days, RWD cars ran very large positive scrub radii (3-4") and had lots of kickback at the steering wheel. FWD cars started the move to negative scrub radii. In fact, VW ran ads in the 70s about how negative scrub radius (I think they called it "steering roll radius") on the Golf/Rabbit made them more stable under braking and acceleration on split surfaces (one wheel on ice or gravel). They had less steering kick back over bumps, but I also thought they had less "feel" because of it.

I've never seen a published scrub radius for the Twins, but I suspect it is slightly negative (~-20mm???), like most modern strut suspended cars. The effect of making it slightly less negative with wheel offset is likely small in comparison to the effect of the much wider tires.

The engineer in me wishes I had the $$ to do a direct comparison - same tires, different wheel offsets. :bonk:

Camber bolts will get you 1.0-1.3 of additional camber. Stock is very close to 0. Rear will have about 1.5 or more with the springs. Ideally, for this car you want more camber in the front for handling purposes. So you need to max out the camber bolts or use two sets(some say it is potentially dangerous). .5 more camber in the front than rear is a good starting point.

Having lighter wheels is definitely a plus espeically if you work on your car....gains are minimal but you can feel the slight difference behind the wheel and accelerating.

Hey, my Miro 398's just came in today. 18x8.5 and I just weighed one. Right at 21.6 lbs, so that should come in lighter than the stock wheels and tires