Since the GRM $2000 Challenge GTW and GTN tire classes are restricted to 200TW and above tires, and drag radials tend to have a lower TW rating(as pointed out in one of the challenge video calls), it stands to reason that a lot of competitors are going to be running the quarter mile on their autocross tires. I'm looking for opinions on how to balance the two as well as possible, or (if the budget is there), see if it makes sense to buy a couple of low-ish TW rating street tires (like Riken Raptors) for the drag portion of the event.
I was originally considering the Bridgestone RE-71RS since it can be had in 15" diameter, but I am wondering if the sidewall is too hard to make it fast (or safe) for the drag strip. Are there any better solutions for keeping lots of later grip, while still having a bit of sidewall flex? In my case, I'd likely be stretching 225 width tires onto a 7" wheel, but I'm curious about what would work best in general, not just for that circumstance.
Finally, I have mostly run street tires and R-comps down the drag strip, so have little experience with 200TW tires there. The only time I did was on a Miata with a stock engine, so traction was not exactly an issue. Does it make more sense to try to use a pair of normal street tires, if they fit the budget?
Sidewall flex can be controlled with air pressure. 200tw tires do just fine hooking up, if you air them down into the teens. Getting the temp into the sweet spot for that model is also key. Burn out box or tire blankets.
BTW, 225 on a 7 is a pinch, not a stretch. 225's are way better on at least an 8, if not a 9.
In reply to Andy Hollis :
Thank you. I stand corrected on the terminology. I have 15x7s already with the car, so there's no budget hit for them. I also have 17x9.5s for a small hit to the budget, but I am guessing there's nothing 225 width out there that'll fit them, so I'd need to move up to GTW. Not terrible, just not preferred.
Andy Hollis said:
200tw tires do just fine hooking up, if you air them down into the teens.
General consensus from people running them in gainesville agrees with them being better with low pressure, but not anything considered "good". Your data driven autocross stuff is great-do you have some on drag stuff?
In reply to eastsideTim :
I had better 60' times with aired down allseasons than R comp tires even though the rubber was significantly grippier. Maybe my car was just too light to make those stiff sidewalls work? They really didn't like to be "spiked" like a tire with soft sidewalls.
On the other hand, it was no contest when cornering, although the track officials tend to frown on slaloming around the timing lights...
If everyone else has the same constraints, I wouldn't sweat it too much.
