[Goldcomet]

I'm looking at a set of 18" polished Bullitts to replace my stock 17' painted Bullitts. Does anyone know from experenance if they are the same diameter as the 17's and will go on without adjusting anything, or will I have to change the settings. They do have TPMS sensors that may have to be programed and if the tire size has to be, can a dealer do it? I don't have a programmer such as a SCT or Preditor (next on my list to buy) and can't afford one if I buy the tires & wheels. Seems like I remember reading someone switched 17's to 18's without changing anything, but I may be wrong. Anyone that has please chime in, especially if you have an 07 on up, because of TPMS.

[07 Boss]

The difference in diameter between 17" rims and 18" rims is 1". Mcfly!

[07 Boss]

Seriously, it all depends on what tires you get. If you get the same tread width and aspect ratio there will be a 1" difference. If you want the same size as you have now you have to get tires with a 1/2" less sidewall height. I went from 27" diameter tire to a 28.8" tire with the same rim. Rim size does not effect the overall diameter. Rim and tire size combined determins that.

I think for the TPMS you may have to buy new bands but I'm not sure 'cause I don't have them.

[Goldcomet]

I figured it would be different, but I hoped I'd get lucky. Thanks for the info Boss

[Goldcomet]

These are the factory 18" polished bullitts, 235/50-18

[2006GTARPD3]

I just went from factory 17 in alloy bullits to 18 DD bullits.

No clearance issues, just diff tire size and a better ride

[Goldcomet]

Did you have to reset anything in your computer?

[2006GTARPD3]

Nope. Just make sure if you get a directional tire the arrow goes the right way.

No need to adjust anything tuner wise. Thats really only for gears.

On a side note: I looked in my SCT for the paramter change selection and couldnt find it :/

[Goldcomet]

Thanks for the replies and I repped both of you.

[1rnkpny]

235/50/18 should be approx the same diameter as the 235/55/17.
235/50/18 have a side wall height of approx 117.5mm and the 235/55/17 have a sidewall of 129.25mm. That is your 1/2 difference that you needed. The speedometer will not change, and you will need the 18" band for the TPMS. Other than that you are good to go!

Get em' and enjoy em!

[Goldcomet]

1RNKPNY these have the bands and sensors and are off an 09, that's why I was hoping I could just slap em on and run, but these cars are so sensitive to changes that's why I asked. I didn't know the difference with diameter and you found it for me. I'm repping you, Thanks all for the help. I'm meeting these people at 4pm and hope they haven't sold by then. I have really wanted these since I bought my car, but they're usually for sale 500-3000 miles away and the shipping kills any deal I'd get. These are right by me.

[Justdoit04]

Goldcomet ... like the movie reference in your sig ... I just hope it isn't a patronage to PVT Pyle in that movie haha

[Goldcomet]

No just that there's so many black Mustangs but I wanted one so bad and was finally able to swing it, it really means a lot to me. That line from the movie really sums it up.

[Jucostud]

Do th new wheels have sensors in them already? If not u will have to swap them over. If they do have sensors than u just need to ge them reprogrammed... Lots of places will do that foe free. Your speedo will stay the same

[cusp]

Originally Posted by Goldcomet I'm looking at a set of 18" polished Bullitts to replace my stock 17' painted Bullitts. Does anyone know from experenance if they are the same diameter as the 17's and will go on without adjusting anything, or will I have to change the settings. They do have TPMS sensors that may have to be programed and if the tire size has to be, can a dealer do it? I don't have a programmer such as a SCT or Preditor (next on my list to buy) and can't afford one if I buy the tires & wheels. Seems like I remember reading someone switched 17's to 18's without changing anything, but I may be wrong. Anyone that has please chime in, especially if you have an 07 on up, because of TPMS.

The stock painted bullitts with stock tires are 27.18" diameter.
With 18" wheels and the 235X50 tires the Diameter is 27.25.
You will be moving 1/4 of one percent faster at the same RPM than before.

[slows197]

well i went from the 17 inch stock bullets to 18 chrome bullets that have the offset for 99-04 cars. i was able to run 275s up front.

[1rnkpny]

Originally Posted by Goldcomet 1RNKPNY these have the bands and sensors and are off an 09, that's why I was hoping I could just slap em on and run, but these cars are so sensitive to changes that's why I asked. I didn't know the difference with diameter and you found it for me. I'm repping you, Thanks all for the help. I'm meeting these people at 4pm and hope they haven't sold by then. I have really wanted these since I bought my car, but they're usually for sale 500-3000 miles away and the shipping kills any deal I'd get. These are right by me.

Or remove the sensors from the 17's and install them with the bands that are on the 18's. Then you don't have to worry about reprogramming. Keep the other ones for spares if something happens.

[Jucostud]

Factory bands aren't reusable. They are pressed onto the wheel

[1rnkpny]

Interesting

[07 Boss]

Originally Posted by 2006GTARPD3 No need to adjust anything tuner wise. Thats really only for gears. On a side note: I looked in my SCT for the paramter change selection and couldnt find it :/

That's not entirely true. Tire size does make as much difference as gears when tuning for the speedo. I went from a 27" tire and 771 (I think) tire revolutions per mile, to a 28.8" tire at 700 revolutions per mile. That's about a 10% difference in speed. If I didn't have an adjustment for tire revolutions I would have to put in 3.84 for my 4.10 gear ratio to make my speedo read correct.