Saturn Tire Width – Installing 225’s

by James Walker, Jr. of scR motorsports (2000)

Sorry, no right or wrong answer here.  For those of you who have read the FAQ article on our website which shies away from 225’s, we have some new information based on our ITA experience.  Here goes:

205’s on Stock Wheels

For almost all street driving, 205/50’s or 205/55’s should fit just fine on factory wheels without any concerns for rubbing, touching, etc.  We only say ‘should’ because manufacturer A’s 205 will NOT be the same width as manufacturer B’s 205.  We learned this firsthand in SSC when switching from BFG to Hoosier tires.  Although both read ‘205/50ZR15’ on the sidewall, the Hoosier hit the strut and required 5 mm wheel spacers to make things happy in the wheel well, while the BFG had room to spare.  From our experience, most street tires that claim to be a 205 should fit, and these exceptions are for ‘semi-race’ tires only, but be forewarned – some 205’s might be close and may require 5 mm wheel spacers when used with stock wheels.

205’s on Aftermarket Wheels

Of course, once you start changing wheel width and offset with 205’s, you’re on your own again.  In general, though, if the wheel is correctly sized for the vehicle (15”x7” with a 35-38mm offset, for example), you should be just fine with any 205/50 or 205/55. The ‘93 SL2 shown is shod with 205/55ZR15 tires on 15”x6.5” aluminum wheels.

 

225’s on Stock Wheels

Why?

225’s on Aftermarket Wheels

Now, what about the 225’s?  On the red #34 ITA racecar we DO run 225/45ZR15’s, and they DO fit and they DO NOT rub anything – except the cradle when the steering is at full lock.  So, how do they fit?

On the ITA car we are using 15”x7” wheels with a 35 mm offset.  When these wheels were first bolted to the car with Hoosier 225/45’s mounted, the tires were in HARD contact with the struts.  Our solution was to install our 5 mm wheel spacers from the SSC car.  While it made things ‘better’ in the front, the rear still hit HARD.  The 5 mm was not enough.

Our next step was to custom-fabricate 10 mm wheel spacers.  This was a challenge, since with a 10 mm spacer the wheel now was offset beyond the hub centering pilot (the 57 mm “nose” that sticks out of the bearing).  So, while we needed to design spacers with 10 mm of offset, we also needed to make sure the pilot feature would not be lost.

We ended up designing a spacer which had a 57 mm center bore but a 72 mm nose on the wheel-mounting side (this was because our particular wheels had a 72 mm bore for centering).  So, the 57 mm bore in the spacer piloted on the stock bearing pilot, while the wheel piloted on the 72 mm nose on the spacer.  Confused yet?

Note: whenever you use more than 5 mm of spacer you will run into this problem…and rear disc brake cars run into it at 3 mm of spacing.  This is why in 1998 we developed a bearing spacer kit with SPS for rear disc brake cars – we couldn’t run the 5 mm H&R spacers in the rear with our disc brakes.

Ok, so we made up the spacers, mounted them to the car and they fit perfectly! No clearance issues to the strut, all the pilots were concentric…but where did the wheel studs go?

Yep – the stock wheel studs were now WAY too short.  After hunting around we finally found a true racing wheel stud that would fit – and at twice the length of the stock units, they seemed to look like a good candidate.  Until we tried to install them, that is.

Because the wheel studs were SO long, we had to disassemble the front and rear hubs completely to get the proper clearance from the back side to press them in.  Anyone who has ever changed a Saturn stock front wheel stud on the car will understand how a stud twice as long just won’t fit.

Ok, so we had the wheels, tires, spacers, and studs ready to go.  Bolted them on, and it looked GREAT!  There were no issues with rubbing or touching the strut, brake lines, etc.  All was looking good…until…until we fully compressed the front suspension and found that the tire contacted both the inner fender lip and the wheel housing liner.

No problem, it’s a racecar!  Scrap the liner, trim the inner fender lip.  Reinstall and re-measure.  Yea!

So that’s our story on making the Hoosier 225/45ZR15’s fit.  As it stands right now, we have exactly 3 mm between the tire and the strut and 3 mm between the tire and the fender lip.  There just ain’t no more room for tire!

So, What Did We Learn?

Now, what can one learn from this story?

  1. A 225/45ZR15 CAN fit with a few modifications (we don’t have a guess about 225/50’s, but they would be too tall, anyway).
  2. If you buy a ‘skinny’ 225, it might fit fine out of the box, but why not just buy a ‘fat’ 205 instead?
  3. In order to make a ‘fat’ 225 fit, be prepared to iterate through the various roadblocks like we had to.
  4. Every wheel / tire / alignment / strut package WILL be different – your spacing requirements may vary.
  5. If you do install ‘fat’ 225’s, the grip is awesome!

So, in summary, here is our humble, conservative (you would expect something else?) advice:

  1. Screw 225’s on the street! It’s not worth it for a Saturn street car.
  2. Buy a real good ‘fat’ 205/50ZR15 (there are many, many to choose from).
  3. Mount your ‘fat’ 205 on a 15”x7” wheel.
  4. Go fast without having to modify anything (except maybe 5 mm spacers).

If you go the easy route and install a ‘skinny’ 225 because it fits without much modification, you can bet that the performance of that ‘skinny’ 225 will be outperformed by a ‘fat’ 205 every day.  The 205 weighs less, has a smaller diameter, and the widths of the two will be the same anyway.

Unless you’re going to run a ‘fat’ 225 (and go through the efforts to make it fit properly), the benefit of running a ‘skinny’ 225 just isn’t there…unless bragging rights are important to you.

JWJr
teamscR.com