The taller tire also benefits from the added sidewall.

I am in the process of switching from a 26x10x15 to a 28x9x15 and stepping up the gears to match.

 

I was spinning my 26 x 11.5 x 15 ET Streets by the time I was cutting 1.6 sixty foot times. That is when I did the rim screws. The last thing anyone needs is a sawed off valve stem. You also need to ream out the valve stem hole to accept a bigger (metalic) stem.

 

Did your 60 improve after the screws

 

The screws made no difference in my times but they did keep me from having to re-seat the tires and having flats.

 

I may be flirting with danger here, but I haven’t put any rim screws in my wheels and slicks. I just can’t bring myself to drill holes in my Alumistar 2.0s. However, I have marked the slicks, have many runs (100+) on them and they “have not” slipped on the rims.

I’m running 15” x 10” rims w/ Goodyear 28” x 10.0” slicks. Also, 4.30 gears and I have consistent 1.54, 60ft times. Additionally, the Goodyears have the stiff side-walls for heavier cars and I’m not running any tubes (which is a very common practice around here).

WD

 

stiff sidewalls don't need tubes, this is from a M/T rep. Also the non-stiff sidewalls we usually don't run tubes, but they will air down after a day or two, so you can't have them sitting on a car or you'll be refilling it often.

 

I know plenty of people who do not use rim screws and do not have a problem. However my Et Streets did spin and I saw the possibility of problems due to the slippage.

I also use tubes. Why? Although many people don't use them it it the manufacturer's recommendation and ET Streets are considered a tube type tire. Sure tubes add a minimal amount of rotating mass, but they provide an extra layer of safety (if properly installed), and especially with rim screws I figured the tubes were a good idea. Additionally, I have to check tire pressure enough as it is and the concept of increased chances for a leak are simply one more thing to worry about while during a burnout or staging that can potentially interfere with a good reaction time.

I have found generally the less distractions a driver has the better a driver can do their job.

 

That's why I switched to Hoosiers. Their QTPs are equalivelant to the ET streets and they are tubless tires. This year I'm trying their drag radials and I love them. 275-60x15s and I have dead hooked every pass this year. Best 60' 1.48, worst 1.53.

 

I have also been very happy with my new Goodyear slicks this season. They are my first set of Goodyears, I had MTs in the past. The Goodyears with the stiff side-walls hold really well and I'm getting very consistent 60ft times around 1.54. Additionally, they are very stable down track.

WD

 

I'm up to a 32 x 14 MT slick now mounted on a 15" wide rim. I have 8 rim screws on both sides of each rim. I shock the tires with a high rpm transbrake launch and don't want the rims to spin in the tires.

I don't use tubes because I have a stiff sidewall tire but in about 2 weeks, the 9 psi of air I normally have in the tires is down to 2 psi.

I soaped the insides of the tires before installing them but I only had time for one coat. After this race season, I'll pull the tires and put 2 more coats of liquid soap on the inside. This will stop any leaks. The tires don't leak around the bead. The air seeps through the sidewalls.

As for your tire height question, typically racers stuff the tallest tire possible under the fenders. Wide is generally restricted to wheel well opening or a class restriction (10.5 class etc). The taller tire give a longer contact patch on the ground. This will give you better traction than a wide contact patch because a fixed point on the tire will be on the ground longer. Once you determine the tallest tire you can use, then you determine the best gear ratio to use that tall height. I started with 26" tall tires and 3.27 gears. Over the years as my car has gone faster, tires and gears have changed. I'm now at a 32" tall tire and 4.86 gears.

 

Maybe I do need rim-screws! A friend of mine took this picture during a launch this past weekend at the Summit Bracket Series. These are stiff side-wall Goodyears w/ 13.5 PSI. That looks like way too much side-wall wrinkle and possibly getting ready to slip on the rim!

WD