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How much does wide tires affect speed ?


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We did a WRL race last weekend and had few drag races on the COTA straigts with an identical car as ours. The other car has narrower tires (225 vs 245) and  10-15hp less. 

However it was pretty even on the long straigts, I think we gained a little but not much.


Could this be due to the tire width / pressure? I would expect us to be quicker on the straigts.


Both cars looks identical (NC miatas)

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Figure 0.9" width difference + 24.5" Tire Height  x 2 tires  = 0.30625sqft


Cd could be about 1.2 for an open wheel if you don't have it covered.  


At 90mph its costing you about 1.786 HP 






 - Ride height, mirrors, rake, under-trays, window nets, intake position, radiator ducting, fender liners.  All of this would impact the speed about the same or more.  

Edited by LuckyKid
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No. There are so many variables it's not even possible to compare based on a race setting. Unless both cars are on the gas EXACTLY at the same time and moving from the same speed. You can't get any real data unless there is a big delta in speed/power between the cars. You can be faster than him, but if he's back to WOT a second sooner, that car may appear to pull away (or stay even) when it really isn't. 

And there are probably a dozen other variables (see above). 

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