94gt
Well-Known Member
- Thread starter
- #1
I am just full of questions on tires this week, but I did finally get new tires/wheels ordered, and I am on my desk happened to be the Roush warranty (just got it back a week ago from adding a Phase 2 to it, which has prompted my need for new tires).
Long story short, I am reading that PCM/BCM must be adjusted for new tire/wheel size, and I went as close as I could for overall wheel height:
Old: 275/40/19- 27.66" overall 729.11 REV/Mile
New: 305/35/19 -27.4" overall 736.06 REV/Mile
Overall height difference is -0.22"
Overall REV/Mile is +6.95
Speedo difference is 0.2MPH slower at 20, and on the high end it is 1.0MPH slower at 90, based on the tire calculator I used.
Does this minimal difference require an update, or if that within the tolerance of error for the configuration given tread wear, etc.?
Do most shops have the ability to make the needed changes,or since the car has a Roush tune I will need to take it to a Roush dealer?
Long story short, I am reading that PCM/BCM must be adjusted for new tire/wheel size, and I went as close as I could for overall wheel height:
Old: 275/40/19- 27.66" overall 729.11 REV/Mile
New: 305/35/19 -27.4" overall 736.06 REV/Mile
Overall height difference is -0.22"
Overall REV/Mile is +6.95
Speedo difference is 0.2MPH slower at 20, and on the high end it is 1.0MPH slower at 90, based on the tire calculator I used.
Does this minimal difference require an update, or if that within the tolerance of error for the configuration given tread wear, etc.?
Do most shops have the ability to make the needed changes,or since the car has a Roush tune I will need to take it to a Roush dealer?
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