Fitting tires and wheels when an off-the-shelf option isn’t listed

J.G.
By J.G. Pasterjak
Aug 18, 2022 | tires, wheels, Shop Work, fitment, Wheels & Tires | Posted in Shop Work , Tires & Wheels , News and Notes | From the Aug. 2022 issue | Never miss an article

Photography by J.G. Pasterjak

It feels awkward referring to our 1991 Toyota MR2 Turbo as an “older” car. After all, we still remember it winning our Editors’ Choice award as the best new car back when it came out. That we drove that first mid-engine turbo Toyota more than 30 years ago seems fairly absurd, yet here we are.

So when our MR2 needed some new wheels and tires, we ran into some issues. We couldn’t simply hop onto Tire Rack’s website and place our order with a few clicks. The second-generation MR2 is notoriously tricky to fit with modern wheels and tires. In fact, that’s a common issue in our world, especially when the car in question is slightly unusual and a few years older. 

This MR2 was originally equipped with 14-inch wheels–Toyota eventually moved to 15s a few years later–but you can already see the problem with trying to find new tires. Thanks to our car’s staggered fitment, Tire Rack doesn’t list any stock-sized tires for our car. 

Nothing.

The optional 15-inch setup doesn’t help, either, as Tire Rack shows just a single option for tires. We needed to look at modernizing our MR2, and we almost had to work backward. First, we needed to identify some appropriate tires, then find some wheels to fit them. 

Step 1: Tire Hunt

We knew we wanted an extremely sporty tire but not a dedicated track model. Most of today’s 200tw rubber in the extreme-performance summer category would fill our needs nicely. 

[Ultimate track tire guide | 200tw, 100tw, street-legal track and R-comps]

This MR2 is not going to be an everyday commuter or a “fighting for the last hundredth” track car, but it needed to be able to do mundane daily duty when the mood struck, along with an autocross or track day without needing a tire change. The 200tw scene is essentially built on that ethos.

For sizes, our most extreme limiting factor was the overall diameter in the front. The original 195/60R14 tires measured about 23 inches tall, and due to the proximity of the spring perch to the hub, we measured our maximum possible tire diameter at about 24.5 inches. Switching to coil-overs provides more options because it frees up some space, but we weren’t quite ready to make that leap. 

Our MR2 originally ran a 205/60R14 rear tire, and that size is pretty much NLA. However, we had a lot of room vertically between the hub and the perch, meaning our biggest limiting factor was width. 

So we started to look at modern tires that would provide suitable outside diameters while still (hopefully) clearing our fenders. We saw 15- and 16-inch sizes available, but wheel availability and the additional desired width in the rear weren’t always options in those diameters. In the end, a 17-inch was seen as the best all-around use of resources.

As soon as our new König Hexaform wheels arrived, we test-fit them to make sure our measurements checked out. Once they bolted up smoothly, we felt safe having our Falken tires mounted.

The front wheels had good clearance from the strut housings, but the distance from the wheel to the spring perch on SW20-chassis Toyota MR2 is restrictive. A short tire is a must for cars with stock spring perches.

The rears have plenty of vertical room, but our 9.5-inch-wide wheels were pretty cozy with the strut housings. A favorable sidewall profile makes rear fitment much tidier.

At 23.8 inches tall, a 215/40R17 front tire seemed like the best fit. For the rear, we wanted to fill out the wheel wells and take advantage of the available space, but we didn’t want to get into modifying the sheet metal for clearance. Preliminary measurements showed we had a little more than 10 inches of space between the strut and the fender lip, and the 10-inch-wide, 24.8-inch-tall 245/40R17 tire looked like a good fit.

Taking all this data and cross-referencing what we could use with the companies that had those sizes in a tire we liked led us to the Falken Azenis RT660. While our testing has shown that other 200tw tires may be able to run an absolute faster lap time, the Azenis is still regarded as one of the best tires in the category for all-around performance on both street and track.

Step 2: Wheel Shopping

Now for wheels. When we bought the MR2, it wore a set of Derpmaster 3000 alloys, likely bought via some Balkan eBay pirate clone site that stole everyone’s credit card number after it sent them crappy wheels. Sure, the wheels were ugly, but they seemed to be of suspect quality as well. 

So while anything would be an upgrade, we still wanted a high-quality wheel that properly fit and also enhanced the MR2’s retro vibe since this car is now older than most of the NFL’s starting lineup. And, as with our tire situation, we thought our wheel choice would be tightly limited.

A flow-formed wheel seemed like the proper answer here. Creating a flow-formed wheel involves running an aluminum casting through a machine that uses heat and pressure to create a strong, lightweight barrel. This usually creates a wheel that weighs less than a traditional cast wheel yet costs less than a fully forged model.  

“The tooling for flow forming can be quite expensive, and the learning curve for properly producing wheels can be steep, but the payoff is in increased versatility of the molds,” explains König’s Scott Weiss. “That gives us flexibility down the road that we don’t have with other manufacturing methods and lets us produce wheels to meet more and more specific demands.” As Scott adds, all wheel production ultimately flows from customer demand, but the versatility of flow forming allows König to react to and serve more niche audiences.

König offers a range of flow-formed wheels, so we dove into its catalog for a model that met our specs regarding diameter, width, offset and that all-important bolt pattern. A style that worked well on our rad-era classic would be a major bonus. 

We took measurements and consulted some testimonials. The gallery section of the Fitment Industries website can be an exceptional resource when it comes to finding workable wheel specs for many models of cars. It contains posts from actual users listing wheel specs, tire sizes, car setup and any modifications required to fit the combo together, and it helped us back up our own measurements.

All this research led us to the König Hexaform model: 17x8 inches with 38mm offset up front and 17x9.5 inches with 38mm offset out back. As a bonus, the Hexaform looks a bit like something from the ’90s JDM scene and invokes some of the OEM wheels Toyota offered on the MR2 back in the day. A 17-inch model weighs about 17 to 19 pounds, depending on offset, and figure a street price of about a grand for a set of four. 

The 245/40R17 Falken Azenis RT660s in the rear have a very slight amount of stretch, creating a little extra clearance below the strut housings. Once mounted, it looked like our rear fitments would be fine without any spacers.

The rear tires filled out the wheel wells nicely without any hint of interference on the inside edges. Under full compression, though, we worried there could be some fender interference, so we decided to put a bit of a roll on the rear fenders–just to be safe.

We didn’t massage the rear fenders much–just enough to take the sharp horizontal edge out of play.

Our final product uses modern wheel and tire technology to create a pleasing, retro look while offering modern handling.

Our measurements, however, showed that we might be a little close to the strut housing on the inside of the rear fender, but it would ultimately come down to the shape of the tire once mounted. If we had a clearance issue, we figured we could solve it with a spacer (fingers crossed). 

When our wheels arrived, we first mounted them on the car without tires to confirm fit, as König will not accept returns once tires have been added. This gave us a chance to confirm our measurements and check that our tire would fit fine within a certain margin of error. As we suspected, the inside edge of the rear wheel sat pretty close to the strut housing, but tire shape would ultimately dictate our path.

Time for the moment of truth: We mounted up our Falkens. The rears had a very slight bit of “stretch”–enough to create plenty of clearance between the spinning assembly and the strut housing, precluding any need for a spacer. The fronts, as we suspected, fit fine.

We did put an ever so slight roll on the rear fender lips–mostly to take a sharp edge out of the equation, although we don’t think that lip will ever be in play at our current ride height unless something extremely bad happened. Still, we considered a small fender massage to be a little insurance policy against a disaster, no matter how unlikely.

[Tech tips | Understanding fender rolling, downsizing tires, wheel spacers and what makes a race wheel]

Our final product fits great, looks appropriate and provides performance beyond what Toyota ever intended for these cars. Now we can properly put down the power, turn-in feels fantastic, and there’s traction for days. 

Modern, high-performance rubber can really transform older cars, giving them grip you’ve barely ever dreamed of while retaining uncanny road manners.

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Comments
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BA5
BA5 GRM+ Memberand Reader
6/22/22 4:44 p.m.

When we bought the MR2, it wore a set of Derpmaster 3000 alloys, likely bought via some Balkan eBay pirate clone site that stole everyone’s credit card number after it sent them crappy wheels. Sure, the wheels were ugly, but they seemed to be of suspect quality as well. 

I lulzed at this. 

AnthonyGS (Forum Supporter)
AnthonyGS (Forum Supporter) GRM+ Memberand UltraDork
6/22/22 6:37 p.m.

Those do look really nice.  This has me reconsidering bronze wheels for my new Civic.  They do look great with red.  That combo is almost perfect on the MR2.  I hope they drive incredible too.  How much weight did your car gain per corner? 

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
6/22/22 6:44 p.m.

Why isn't there a site that sells bunches of wheels by diameter, width, bolt pattern, and offset?

 

I know there are wheels out there to fit my 2nd gen rx7 in a 15 x 9 or 15 x10, but I can't find them.  I'm running jegs wheels instead...

Coupefan
Coupefan Reader
6/23/22 1:20 p.m.

You're just called a 1990s vehicle old. I think I'm going to have a miserable day today.  Thanks. 

RobMason
RobMason New Reader
6/24/22 1:47 p.m.

Try finding Autocross/Track tires for a 1957 MGA with 15x4 wheels.

Ended up going with 2006 Hyundai Sonata 16x6 alloys with Hankook 205/55/16 tires. Did a lot of fitment calculations and simulations to find a tire size that fit, was available, and was still close to stock diameter for driving to and from events.

2006 Hyundai Sonata wheels

 

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) GRM+ Memberand PowerDork
6/24/22 7:23 p.m.
RobMason said:

Try finding Autocross/Track tires for a 1957 MGA with 15x4 wheels.

Ended up going with 2006 Hyundai Sonata 16x6 alloys with Hankook 205/55/16 tires. Did a lot of fitment calculations and simulations to find a tire size that fit, was available, and was still close to stock diameter for driving to and from events.

2006 Hyundai Sonata wheels

 

Let's hear it for the MGA! Hoping to see it with the new engine soon.

miatafan
miatafan GRM+ Memberand Reader
6/25/22 1:47 p.m.

Fitment Industries has a pretty good selection of wheels

JG Pasterjak
JG Pasterjak Production/Art Director
6/25/22 6:59 p.m.
Coupefan said:

You're just called a 1990s vehicle old. I think I'm going to have a miserable day today.  Thanks. 

I drove my first MR2 Turbo as a press loaner if that makes you feel any better.

JG Pasterjak
JG Pasterjak Production/Art Director
6/25/22 7:00 p.m.
AnthonyGS (Forum Supporter) said:

Those do look really nice.  This has me reconsidering bronze wheels for my new Civic.  They do look great with red.  That combo is almost perfect on the MR2.  I hope they drive incredible too.  How much weight did your car gain per corner? 

Those old wheels were made from recycled Bosnian tanks I think. Weight was essentially the same. Lighter in the front even I think. I'll look up my numbers.

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