Changing Rim/Tire Size Consequences

[triker]

I picked up a deep impact blue Mustang GT Premium (non performance pack) with the 265/35/20 tires (Pirelli PZero summer-only) over the weekend and need to either get all seasons for the car or a separate set of winter-only tires and wheels to get me through April.

I called a few tire shops around and they seem to be able to get what I need in 20" all seasons (Continental ExtremeContact DWS). I've also considered getting a separate set of wheels and tires since it'll probably end up being close to the same cost.

I called a local Ford parts department (not where I bought the vehicle--due to distance) and was accosted by the parts manager stating there was no way I had 265/35/20s on my car because there "would be no tire to ride on [sic]." I was also informed it would be cost prohibitive to change to 18" rims from the 20" because of computer "replacement" and additional TPMS sensors. I call bull on this as I've seen this exact thing listed as done with several posts on this forum and elsewhere.

I just wanted to verify I can in fact put 18s with winter tires on my car if I can find a set of rims to go with it. Finding TPMS sensors may be a different story, but with time I'm sure I can find those as well.

Thoughts? Suggestions?

Thanks!

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[2Cool]

All you need to do is pick a tire with the right sidewall and width to end up with similar overall diameter to your current wheel assembly. So for an 18" wheel you could choose a 265/45-18 tire, and be .4% of the stock tire circumference. Your computer would see no real difference in revolutions and only a very slight change in speedo reading (ex you would actually be going 70.3mph when your speedo reads 70).

Just do a search for "tire size comparer" and find out the right width and offset to get close to your stock setup. Something like http://www.rimsntires.com/specspro.jsp

 

[SuperSnake]

Interesting thread. I want to do the exact opposite. Go from stock 18s to 20. Never thought if that stuff.

I was under the impression that your car and my car would be set-up identically with the exception of wheel size. So, very easy to swap. No?

 

[JimmyTwoTimes]

I just wanted to verify I can in fact put 18s with winter tires on my car if I can find a set of rims to go with it. Finding TPMS sensors may be a different story, but with time I'm sure I can find those as well.

Thoughts? Suggestions?

Thanks!

Yes. You can put 18's with winter tires on your car. The 20" wheels do not include the upgraded Brembo brakes from the performance package, just keep the standard GT brakes, so you can definitely put 18's on over them (I have 18's with my winter tires on now even though the car came with 20's). I got four wheels (admittedly cheap wheels, but they look fine) with Michelin XIce Xi3 tires for $1400 delivered from TireRack.

 

[1320']

Something to consider...

In terms of performance going from a 20" to an 18" will be fairly dramatic. Take for example my plan in getting 18 X 9 TSW Nurburgrings with 265/35/18 Michelin PSS's for summer work when I get my car. That alone is going to shave 44.4 lbs off the car, while keeping the winter tires with all seasons for fall/winter/spring.

 

[triker]

Thanks for the information! I'm planning on putting all seasons on my 20s just because this car is going to be my daily driver and with rain and other (even summertime) weather we experience, I want the improved wet road traction of the all seasons. I think before next winter I will get a set of 18s with a more winter-capable tire to use between November and the end of March.

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