Continuing where we went off on Part I of this guide, we are going to hypothetically apply the concepts of wheel and tire selection on two cars with two differing objectives. One is a dedicated race car for conesport and circuit races, and the other is a daily driver that is wanting of a bit of aesthetic improvement. What’s so interesting about these two case studies is that the framework we previously presented is applicable to such disparate intentions. Or at least we aim to.
Do read the first part of this guide so you know what we are on about. Done? Read on.
Quite simply, the basic steps for acquiring wheels and tires as presented in the first part of this series is as follows:
- Pick tires first
- Pick wheels that would allow the tires to work on your car
- Canvass for prices and best deals
The analysis framework for each part is as follows:
Purpose: intended use of car, goals to achieve
Physical considerations: size that would fit car, effect on speedometer accuracy
Considerations on quality: longevity of tire as inadequately measured by treadwear, reputation of brand of tire, traction or grippiness of tire in the conditions it will be subjected to,
Subjective considerations: tread pattern, curb appeal, reputation of brand of tire
Financial considerations: price
Purpose: intended use of car (complementary to tire selection)
Physical considerations: lightness of wheel, diameter that would clear brake system, caliper-spoke clearance, bolt pattern, width that would best accommodate tire, offset to avoid the tire fouling in the wheelwell and fender
Considerations on quality: durability ascertained by brand’s reputation and by relevant industry certification (VIA, etc.)
Subjective considerations: wheel design, curb appeal, reputation of brand of wheel, etc.
Financial considerations: price
Of course, the above considerations may not be complete. At the same time, there may be most that you not need consider at all. It is hoped that given the above, you can better analyse the case studies below.
Case A: Project Elantra
As you know, Project Elantra is a dedicated race car for conesport and circuit races. It’s currently running on Rota Slipstreams and 195/50 R15 tires. We believe we can do better with the car in increasing maximum grip by fitting the widest possible front tires in it.
We are considering tire sizes available in the Federal Tires range. Federal Tires are the spec tire brand for the 2013 Slalom championship. We sell Federals at the kuhol.net online store, too.
Our inspiration and pegpeg is the Spoon Civic EK featured in the Best Motoring International 33 DVD. Fitted with 255/40R17 front, 215/45R17 rear tires, it entry oversteered like a sunovabitch at the Tsukuba Circuit and won over other K20A cars with dorikin Tsuchiya at the wheel. Such a staggered tire setup for FWD is uncommon in the racing circles we hover around in, so we think such a handling balance would be most advantageous to us.
Both tire sizes are available with the Federal SS595 tire, one of the highest-spec tire models allowed in Slalom. We assume in this exercise that we wish to qualify for slalom races, and thus will discuss Federals.
Using the Miata Tire Calculator, we can compare the two wider 17″ sizes with the current 15-inchers.
Not only are the new tires wider, they are 10% taller than the previous setup. The decrease in gearing is immaterial to us, as the car is turbocharged and the engine can power through the gearing change. Accommodating the 30mm (1.18″) increase in radius, ceteris paribus, can be done by increasing vehicle height if necessitated. But combining the radius increase with the width increase? Definitely, fitting the front pair of 255’s will be a bitch. That’s where wheel offset selection will come to play.
Using the willtheyfit.com tire calculator, we can see graphically the extent of the problem of fitment. We inputted the specs of the current rolling stock and we assumed a 17×9″ wheel with offset of 40 for the proposed front setup.
First observation: if you maintain the same offset, any wheel width increase will be equally proportioned between poke (centerline to outside rim) and inset (centerline to inside rim).
Second: There is an additional 30mm to account towards inset. There is not enough inner wheelwell clearance in Project Elantra to accomodate 30mm. As much as possible, inset must not differ drastically. from the present setup, as cutting up a fender is easier than eking more space towards the inner wheelwell, beyond which lies the powertrain. Let’s assume that, accounting for steering axes and negative camber settings, remaining inset clearance without fouling is 5mm. Thus, we need a minimum decrease of 25mm of wheel offset.
Going back to willtheyfit.com:
As you can see, the tires be well-accommodated with a 17×9″ wheel with offset of 15mm. With a little bit of fender persuasion, of course.
Now, the issue is finding the wheels that would work. It will not be easy. A combination of uncommon specifications like the wheel size, offset, and required bolt pattern of 4×114 conspire against acquiring an off-the-shelf wheel that meets needed requirements. There must be a bit of compromise on our end.
The easiest compromise is offset. If we can locate a 17×9″ wheel with say, a 35mm offset, we can easily locate 1″ thick spacers that would get us to where we want. But 4×114 is a difficult bolt pattern to find big-diameter wheels for. If we are desperate, converting to a 5×114 bolt pattern may be worthwhile, but would cost a pretty coin. Options include trawling the surplasans for some hubs that would bolt on, or sending the existing hubs to a machine shop for them punch out a knurl or four, per wheel.
Cost is a major criterion for us. Even if we do find the Cinderella wheel to fit our fairy-tale tires, can we afford them? Thus, financial considerations constrain us to remain with the current 15″ setup.
We plan on gearing up for 2014 instead. Who knows what the tire regulations will be like next year? We shall evaluate our options after we have seen and digested the latest edition of the Slalom rulebook.
Case B: Tarting up a Carens
Our daily driver is a 2011 Kia Carens. We think it’s overall exterior design is a bit humdrum, worsened by the “dinkyness of the 15-inch steel casters” fitted as standard. A wheel change will do much to improve its aesthetic appearance, and depending on what tire we fit, will improve handling by a bit. No sticky tires though – this is our urban assault vehicle.
Tire selection is quite easy in this case. A cursory look at the tire inflation information sticker, located at the driver’s side B-pillar, reveals that the widest OEM tire fitment for the Carens is 225/50R17. We’d like to go with that, please.
In the Federal Tires catalog, we have a choice of two tire models in the subject size – the SS595 and the Formoza AZ01.
They cost approximately the same, so the decision boils down to form and function. Agreed, the SS595 is the more interesting tread pattern. But since this will be for a daily driver, we would lean towards the AZ01’s asymmetric design and quiet tread pattern. Pragmatism over emotion – how great decisions are made.
Now that we have the perfect tire, how about wheels? The Carens has a 5×114.3 bolt pattern, thus allowing for a myriad of wheel selections. We can get some aftermarket rims, or troll about for some slightly used OEM alloys.
If you ask us, our desire as far as aesthetics is concerned is to maintain an OEM-esque appearance. This is why we’re on the prowl for any used 17″ wheel from a Kia, likely a Sportage or similar model. A design in consideration is one from a first-gen Mazda 3, which looks quite similar to the standard steel wheel covers.
Aftermarket options are tempting and numerous. Whatever wheel we end up getting, it should have a width of 7 to 7.5 inches to maintain the squareness of the tire’s sidewall. No hella-effing-flush here.
The car’s stock Kumho Solus tires are warranting replacement in a few months. We do not know if we can go 17’s when the time comes. If not, given budget constraints, we will just get stock replacements. There are Federals available in 205/65R15 – in this case, the Formoza FD2. We’re still covered.
That’s about it for our thoughts on upgrading your car’s wheel/tire setup. If we have more to add, or have seen new innovations in this area, we will have a Part III of this series.
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