I have had this arguement many times with my friend so I decided to see what you guys think. They think that changing out the front 17's (235/45/17) to the stock (215/65/15) will result in a better 1/4 mile time. I told him you would make up the lighter weight with better traction. What do you guys think.

 

swap the rims, and ur notice a difference.

 

If your car has 215/65R15 as stock, then someone has put on the incorrect tire size.You should either have a 205/65 or a 215/60. A 215/65 is taller than stock therefore raising your overall gear ratio which doesn't help acceleration. Now, if you were about running the correct stock tire size, then YES, stock size tires will help you in the 1/4.

First, the 205/65R15 or 215/60R15 is most likely a lighter setup than a 235/45R17 setup. Lower unsprung weight = better acceleration

Second, low profile tires incorporate very stiff sidewalls which make for poor off the line traction. Think of it like this. Narrower tires get more traction simply because the contact patch is longer vs the wide contact patch of the low profile tires. Narrow tires = better off the line traction. Wide tires = better lateral grip



Dave

 

I've been told if you go down to your stock tires, and race a lot to get some compound R tires. because you'll spin so bad in your launch, or you'll bog down. So I'm yet to try it, but I plan too shortly.

 

Try it at the track and see.


But really though, there will be a difference bewteen dragging on 17's vs 15's. With the 15's, your acceleration will be better and your 60ft times will be about .1 faster and that makes usually .2 faster in teh q-mile. Now, wiht the bigger rims, they will decrease acceleration but it will improve your trap speed. Meaning your trap speed should be higher. I have gotten better 60ft times from my 15's vs my 16's. And yes, i do have prrof on time slips.

 

So whats the trick to this? I know that I can't launch over 2400 RPMS with my 17's--I'll spin too much. so when I have my 15s back on it. I can't launch that fast or I'll be sure to slip forever. If I launch at a lower RPM won't I bog down too much?

 

!!!!!!!

 

See, now that wasn't the case for me. When I went from my 17's to 15's my 60 ft times didn't improve any, but by trap speed went up and my ET's went down .2s.

Maybe I just haven't gotten used to launching the car with these wheels yet.