Competition Taller tires cost ET

[jwdeeming]

Here's an unscientific report on what moving from 285 tires to 315s did to my 1/4 mile ETs, all things being as equal as I can make them. Previous best was 14. 9 at 92mph. Now, with 315s, best of only two runs is 15. 5 at 85mph. Guess if I had an endless pile of fun money, it'd be time to put those ARB lockers front and back and drop the gearing ratio. Not any time soon - $igh...



I said "unscientific" because this was as measured by the G-tech. Has anybody ever compared these little toys to an actual time slip at the track? If things aren't too crazy Sunday at Bandimere, I'll try to run that little experiment and post the results here. But it's my first time on the track since High School. I may be a little preoccupied with watching the tree and gauges...



JimD

 

[Mopar-muscle]

jim , the taller tire will slow you down as is changes your final gear ratio .



i never put much stock in gtech readings , if you don't have it set perfectly it will not read correctly .



don't need to watch the gauges much other than bringing up a small amount of boost , just hold a certian RPM , stage as shallow as possible and when you see the last yellow , GO ...

 

[jwdeeming]

"Small amount of boost"?



I've been wondering about the launch for awhile. Isn't it pretty critical that the boost level be exactly the same for each one so you don't vary the reaction time?



It's pretty exciting leaving the line at about 10 to 15 psi but it's hard to hold it there. Once mine sees 10, the needle wants to fly to 30. I DON'T want to be launching up there. Something would give...

 

[fj40charles]

Another about tire size. You're having to move more mass as you up the tire size. Takes more HP/torque to get more weight spinning.



If you want to really show some large numbers on the dyno, I guess you could get some really small tires... ;-)



Charles: