Help a first-time aftermarket wheel customer with questions before purchase!

[white_knight]

Slower acceleration. You'll need to upgrade your power. Turbo. Supercharger.

[Grimlock]

Originally Posted by stratodyne

According to the fitment guide on Tirerack.com, the "recommended" tire size for this wheel is 235/40-17. Unfortunately, there aren't a lot of options for this tire size, especially in the high performance summer tire area (there are mostly “Extreme” summer tires). Would jumping to a 235/45 tire cause any issues with rubbing with a 1” drop? Is there another tire size any of you could recommend to me that would fit the OZ wheels?


I understand that increasing the aspect ratio of the tire will raise the height of the tire, adding rotational inertia, effectively slowing the car down. Also, the added height can also cause the speedometer to become inaccurate. Can any performance shop adjust the calibration of the factory speedometer to match the new tire / wheel combo?

And lastly, I see that TireRack offers the option of purchasing a new set of TPMS sensors. Is this going to be required for use on the Ozs? I noticed that if I elect to choose this option, TireRack will install the new sensors on the wheels before they are shipped to me. Does this mean that the performance company will have to do anything special when installing the wheels? I know that they'll be able to help me get the flush look I desire, but I wasn't sure about the TPMS system.

Here's my situation: I have the RCE springs, and -1.2º of camber of front. I went with 17x8 +45 wheels and 235/45/17 tires. Everything fits fine. The 235/45 tires were cheaper than the available 235/40's. Also, I liked the 235/45 because the extra sidewall height effectively reduces wheel gap by an extra 3/8". Yeah, that extra height does change gearing a bit and change your speedometer and odometer.

The nice thing with the speedometer change is that on my car the speedometer is now accurate (verified with GPS). The odometer reads a bit 'slow' though, but that's okay with me (I put less miles on the car this way).

Even with the wider & taller tires, my new setup is still a couple of pounds lighter than stock. And as a reference, the Michelin PSS tires are 3 lb lighter per tire than the ZII Star Specs. So that's something to consider as well.

I got the additional TPMS sensors installed in my wheels because staring at that light bugs me. I asked for the codes when I got the wheels in case I stumble upon someone with a ATEQ Quickset. I haven't gotten the car reprogramed to the new sensors yet, though. I haven't found the time.



Here's my car with RCE springs, 17x8+45 PF01s, 235/45/17 Michelin Pilot Super Sports:

Originally Posted by stratodyne

With the lack of a TPMS system, wouldn't the ECU be programmed to throw a perpetual tire pressure error on the dash?

Correct.



Let me know if I didn't address something specifically. I made the same choice you are trying to make now, so I have some experience with it.

[Grimlock]

Originally Posted by stratodyne

I don't see any mention of this in TireRack's literature on the wheel itself. There is some information about included hardware, though, but don't think this is what you mean:

"The following wheel-specific hardware will be included with your order at no additional charge.
(4) Required centering ring
(20) Required lugbolt for vehicle (black)"

That's exactly what he means. Just use the new lugs that come with the new wheels. Keep a set of lugs (5) in the trunk to be used with the spare tire. The 'centering rings' are the hubcentric rings. Manufacturers make wheels with an oversized hub bore for most cars, and then use rings to get it down to the right size for different vehicles. Making one size bore plus rings is cheaper than making wheels with different bore sizes.

[Grimlock]

Originally Posted by white_knight

235/40 tyres will throw your speedo off by more than 3%.

Starting from a 215/45/17, a 235/40/17 tire is 0.9% too fast. That means the new tire is smaller than the original. A 235/45/17 is 2.9% too slow, meaning the new tire is taller than the original. Still, neither is off by more than 3%.

I've noticed that my speedometer is actually accurate now with my 235/45/17 tires. Speedometers from the factory are usually set to read high to avoid lawsuits over speeding tickets. Odometers are set to read accurately from the factory.

[stratodyne]

Wow, lots of responses! Thanks guys!

I've spoken with one of the vendors here on the forums, and he's given me some additional insight before I pull the trigger.

Firstly, I've decided on a 225/45/17 tire, specifically the Michelin Pilot Super Sports. Based on my research, these tries seem to be everything I'm looking for in a summer tire.

One thing that was brought up by the Vendor (CSG David, in the above posts), was that simply slapping on the new Eibach springs could prove to be detrimental to my stock struts i.e. premature wearing, thus reducing their life. Knowing this, is it recommended to also purchase aftermarket struts when getting the springs? Since I wont be able to perform any adjustments myself in the future, I'm looking to get a setup that allows me to "set-it-and-forget-it" after the initial settings are dialed in by the shop. Dave suggested coilovers rather than simply springs, but my knowledge on coilovers is slim to none . I'm looking to primarily improve the handling of the car. Dropping the car for looks is a secondary benefit with improved suspension, and is not my focus

Concerning camber, are the BRZ / FRS cars equipped with adjustable camber bolts from the factory? If not, how would this affect the car after the new parts are installed?

Thanks again for everyone's help thusfar!

[Grimlock]

Originally Posted by stratodyne

Wow, lots of responses! Thanks guys!

I've spoken with one of the vendors here on the forums, and he's given me some additional insight before I pull the trigger.

Firstly, I've decided on a 225/45/17 tire, specifically the Michelin Pilot Super Sports. Based on my research, these tries seem to be everything I'm looking for in a summer tire.

One thing that was brought up by the Vendor (CSG David, in the above posts), was that simply slapping on the new Eibach springs could prove to be detrimental to my stock struts i.e. premature wearing, thus reducing their life. Knowing this, is it recommended to also purchase aftermarket struts when getting the springs? Since I wont be able to perform any adjustments myself in the future, I'm looking to get a setup that allows me to "set-it-and-forget-it" after the initial settings are dialed in by the shop. Dave suggested coilovers rather than simply springs, but my knowledge on coilovers is slim to none

Concerning camber, are the BRZ / FRS cars equipped with adjustable camber bolts from the factory? If not, how would this affect the car after the new parts are installed?

Thanks again for everyone's help thusfar!

When I bought my RCE springs I also bought Koni Sport shocks because of the reasons you state. And I didn't want to do the same work twice when I wanted to replace the stock struts.

The BRZ has zero camber modification abilities from the factory. In the front you need to purchase 'crash bolts', which are also called camber bolts, or get adjustable top hats. Inthe back you need to either purchase new adjustable upper control arm bushings or rear lower control arms. I went the crash bolts and upper control arm bushing route.

If you don't get camber adjustment parts, you won't be able to adjust your camber at all. With a 1" drop you probably won't be 'over-cambered' but the alignment may not be where you'd want it. Also, I've seen cars without camber adjustments that have different cambers side-to-side after lowering. That's not going to get you the best handling your car has to offer.

As far as coilovers go, they may have build-in camber adjustment in the front, but you still won't have any for the back. And there are a wide range of coil overs with prices from $600 to $4,000. A good 'sport' coil over is the KW V3 (or RCE equivalent), and they tend to run in the $2,100 range where as a good set of springs and shocks would cost ~$1000. Don't forget to add camber adjustment capabilities, alignment, and labor to those costs.

Personally, I prefer to do something once and do it right so I got springs, shocks, camber adjustment all at the same time.

Also, the 225/45/17 Michelin PSS are a good tire choice.

[CSG David]

Originally Posted by stratodyne

Wow, lots of responses! Thanks guys!

I've spoken with one of the vendors here on the forums, and he's given me some additional insight before I pull the trigger.

Firstly, I've decided on a 225/45/17 tire, specifically the Michelin Pilot Super Sports. Based on my research, these tries seem to be everything I'm looking for in a summer tire.

One thing that was brought up by the Vendor (CSG David, in the above posts), was that simply slapping on the new Eibach springs could prove to be detrimental to my stock struts i.e. premature wearing, thus reducing their life. Knowing this, is it recommended to also purchase aftermarket struts when getting the springs? Since I wont be able to perform any adjustments myself in the future, I'm looking to get a setup that allows me to "set-it-and-forget-it" after the initial settings are dialed in by the shop. Dave suggested coilovers rather than simply springs, but my knowledge on coilovers is slim to none . I'm looking to primarily improve the handling of the car. Dropping the car for looks is a secondary benefit with improved suspension, and is not my focus

Concerning camber, are the BRZ / FRS cars equipped with adjustable camber bolts from the factory? If not, how would this affect the car after the new parts are installed?

Thanks again for everyone's help thusfar!

You have essentially no camber adjustment availability in front. There is no ability to adjust camber in the rear unless you get an aftermarket solution. Use crash bolts that you can get from Subaru for $20 or something cheap to get more camber if you need it. Camber plates are necessary for camber adjustment in front.

Based on your feedback, keeping your car on stock suspension is probably best if you don't mind the ride height. Using crash bolts will help you gain additional camber from the factory and you can maximize the camber for better handling characteristics. Getting a little more camber doesn't kill tire wear as much as people think. It's the toe that kills tires.

[WolfSongX]

One more thing on coil-overs is that they are overkill for the street and have had most of the "comfort" engineered out of them. When I owned my shop, I only recommended coilovers to people who were tracking their cars or to people who were building serious show cars and were going after a certain stance. In all other situations I would recommend a spring and shock with a mild drop, which is about 3/4 of an inch for this car.

Camber bolts are definitely a help but I think that you are going to find that once you head down this path, you are going to get into some serious money for parts you don't understand that require a lot of specialized setup... unless you have a shop that can do performance alignments on race cars, a great deal of the people doing alignments are totally clueless with doing anything past camber bolts (and I've found a few that are clueless with even using those)

I see a lot of potential here for you to wind up being way over your head. My advise is to do things in steps and do a lot of reading in the process. There are some very good discussions on suspension on here that can help you to understand.

[DanoFA20]

Originally Posted by eljefe

I am running a 17x8 +35 wheel, but i have 225/45/17 tires. I am nowhere close to rubbing, and i have an even more aggressive drop than you will have.

Hope this helps. It looks like youve done your research. The speedo difference cant feasibly be adjusted. as far as TPMS i would recommend just transferring your stock ones from your old wheels if you really care (i left mine out.)

same wheel specs i had my tpms swapped

[DanoFA20]

Originally Posted by stratodyne

Hey everyone! I've been reading and re-reading the tire 101 thread, as well as checking fitments and designs of wheels in the Wheels Gallery here on the FT86Club forums (big thanks to DarrenDriven for maintaining the gallery).


Since I lack both the tools and technical ability, I will be having a local performance shop perform the installation of both the chosen wheels / tires, as well as an Eibach Pro spring kit, netting a 1” drop on each corner.

After looking over many designs / widths / heights, I've finally decided on a set of 17x8 OZ Ultraleggeras in Black, as these have the look I desire, but are lighter than the stock wheels, and the 17” diameter should help minimize the amount of rotational inertia I'll be adding to each corner, but I have numerous questions on installation concerning TPMS, speedometer, rubbing, etc.

According to the fitment guide on Tirerack.com, the "recommended" tire size for this wheel is 235/40-17. Unfortunately, there aren't a lot of options for this tire size, especially in the high performance summer tire area (there are mostly “Extreme” summer tires). Would jumping to a 235/45 tire cause any issues with rubbing with a 1” drop? Is there another tire size any of you could recommend to me that would fit the OZ wheels?


I understand that increasing the aspect ratio of the tire will raise the height of the tire, adding rotational inertia, effectively slowing the car down. Also, the added height can also cause the speedometer to become inaccurate. Can any performance shop adjust the calibration of the factory speedometer to match the new tire / wheel combo?


And lastly, I see that TireRack offers the option of purchasing a new set of TPMS sensors. Is this going to be required for use on the Ozs? I noticed that if I elect to choose this option, TireRack will install the new sensors on the wheels before they are shipped to me. Does this mean that the performance company will have to do anything special when installing the wheels? I know that they'll be able to help me get the flush look I desire, but I wasn't sure about the TPMS system.


I've never purchased a set of aftermarket wheels / tires for any car, so I appreciate any and all advice you guys can offer to me! Thanks!

have the shop swap your tpms sensors its cheaper and easy just order the wheels and tires separately get 225/45/17 they fit flush as a glove.
id also reccomend +35 offset no rubbing at all still a tad of gap on 1inch drop