OK, unfortunately I must show my ignorance again, but you all are so nice you'll go easy on me, right?

I read something recently in a post about using spacers when changing from 17" to 18" wheels and now I can't find the post again to see if it applies to me to save my life.

I will be using my stock 17" wheels for snows (Blizzak 225/55/17 - that size tire will work, right?) and then will use 18" OEM fanblades w/ stock KDWS 235/50/18 tires in the summer. Do I need spacers when I change to the 18" wheels? If so, why why why??

 

If you're using factory rims and tires sizes appropriate for the rim, then I don't see a problem.

Spacers are used in situations where the inside of the wheel rubs on the suspension or other body components. They're also used when upgrading brake calipers, where the caliper interferes with the rim.

I installed spacers on my rear wheel because I am having the rim widened two inches. Without the spacer, the tire would rub on the rear strut.

 

You won't need the spacers for the wheel change you are describing. Enjoy!

 

^What they said. I don't see a problem with 225 width tires, as they're only 10mm narrower than the stock tire that comes on that rim (but narrow tires are better in the snow), but if a tire isn't wide enough for the rim, the bead might not seal well and the tire could leak, or in extreme cases it could come off the rim

 

The 18" Ford wheels are 8.5" wide, so they support a 235mm wide tire and have been designed to fit the wheel hubs with the appropriate backspacing. Thanks, Ford!

 

So I call Tire Rack this morning to order my Blizzaks and I tell them I want 225/55/17 WS50's. He asks me what car I have etc and then told me there is NO WAY I can use that size tire on my 17" factory rims (?) because they are too short and too narrow for the load and "all the other stuff going on with that car". It was then suggested that I get Dunlap M3 something or other for $170/tire. Not going to happen.

OK, correct me if I'm wrong but aren't the 17" rims 8" in diameter (not 8.5 like the 18")? If that's true than why can't I safely go from 235/55 to 225/55?

I am a confused individual at this point, please help. I KNOW there are mustang owners out there with the WS50 Blizzaks on their 17" rims - what size tires do you have?

 

I found this note at Ford Racing on swapping wheels.
Note: For vehicles with 16" wheels from the factory: -installing 17" x 8" wheels, use steering stop 4R3Z-3932-BA -Installing 18" x 8.5" or 18" x 9.5" wheels, use steering stop 6R3Z-3932-CA
For vehicles with 17" wheels from the factory: -installing 18" x 8.5" or 18" x 9.5" wheels, use steering stop 6R3Z-3932-CA

I don't know if that helps.

I recently had my 17" Silver Bullitts replaced with 18" Polished Bullitts and they did not replace the stops! I had to go back in to have the stops put in and the wheels realigned.

I would recommend having your winter rims the same size to avoid problems.

 

According to Bridgestone, the 225/55/17 Blizzak WS-50 is approved for rims 6.8-8.0 inches.

See PDF link below.

http://productcat.bridgestonetire.co.../pp_738586.pdf

 

He's totally full of it.

 

Yeah it does help - I'll be changing to 18" tires/rims in the spring. Thanks!

 

Thank you I thought maybe I read that wrong....

 

And thank you too. I guess I just don't trust my own judgement. I even made sure the load (1609 lbs per tire) and speed rating (Q) were OK too for the car before ordering. I guess they could argue with me about the speed rating but I figure I'm not going to be going 100 mph in the winter...

Thanks again

 

Sounds like you are already tire smart. You checked all the right things.

 

For advising against installing a tire that is both smaller in diameter and narrower in width than the O.E fitment despite matching the load rating.

I would have said the same thing. The tire industry is rife with lawsuits for this very thing.

The general rule of thumb for tires is to go up, not down in size or rating.

Here is a reasonably priced alternative to the 225/45R17 and its in a 235/55R17

http://www.tirerack.com/tires/tires....e1=yes&place=5

--->edit<---

Check with Bridgestone and/or Ford, Ford might be reticent in giving their okay, but Bridgestone will probably be more helpful. I noticed that the tire the TR guy was reccomending was an H-rated tire as well.

 

OK, I know a 225/55 is narrower, but how does it end up smaller in diameter if the tire height is the same? I also did the calculations for acceptable tire size change - under 3% was recommended - and going from 235/55 to 225/55 was a 1.59% change (or .59% - can't read my own writing!) with speedo change of +1.60 mph. Not being a smart butt here, just looking to get educated...maybe I'm not understanding how diameter is measured?

I can appreciate that - we do live in a sue happy culture!

Yeah, I did consider the X-ice, and very well may end up getting them. I wanted the Blizzaks because from what I gather they are highly rated in snow/ice and I want to be able to travel north in the winter (although they are not so great on dry pavement).