Rim width and it effects on tires..........

In the process of sticking a new rear suspension and housing under the car, I mounted one of my m/t 13 x 31 slicks on the new rims.



Sidewall bulge is 1.5" more, and Nick the tread width stayed the same at 13.1 inches.............. This is going from a 12" wide prostar to a 15" wide alumastar, the alumastar despite the added width is 2.2#s lighter.

The Alumastars have a rolled edge making the rim screw placement a pita, I rigged a hillbilly mill and fixed the problem...........




I will add with the 12" rims the outer 1/4" to 1/2" edges of the slick were not being used, after 8 passes they were as smooth as they were prior to being installed. I also see where I had some preloading issues that explain the right movement on launch.

you'll be glad you did this.you gona redo the rearend too,axles etc?

Years ago on my Ranchero I had to mill similar recesses for correct rim screw hole depth (had thick-ass aluminum slots with a thick-ass bead/flange). Worked great & didn't weaken anything. I have to admit I have never been real comfortable with having a wider rim width than the slick tread width. I have seen where it can sometimes cause the "rim is too wide" cupping effect on the center of the slick's tread surface.


On a "smaller" sized slick, I feel that having the rim width as close to the slick tread width as possible is the best of both worlds. Your less likely to "cup" the center of the slick tread (ride the outsides of the tread) from the rim being wider, or "crown" the slick tread (miss the outsides of the tread) from the rim being too narrow.


On the "middle" sized slicks I think you still need to have the rim & slick widths as close to being the same as possible if "normal" air pressure numbers are used. On the other hand if the combo works best with air pressures in the middle to lower range (but still no visible wrinkles when staging) you can get away with using a little narrower rim and still get a good contact patch out to the ends.


On the "biggest" slicks (33.5 x 16/17 & 34.5 x 16/17) it can be hard to avoid running a rim that's narrower to some degree than the slick tread surface because of the 16x16 rim max. But when you get to these slick sizes and decent power numbers, a lot of times your using a combo of middle to lower air pressure numbers combined with wheelspeed. So you can sometimes end up with some really weird looking tread patterns regardless of the rim to tread width ratio.

cool40 wrote:you'll be glad you did this.you gona redo the rearend too,axles etc?

This housing is an old factory 9" that has about 20#s of brackets welded to it from the 15 years of changes lol. Will also be replacing the 35 spline axles to 40 spline, REM finished gears and bearings, ball bearing pinion support, Mike Duffy is gonna build me a set of bigger, stronger ladder bars to replace the ones I have. He sure can spend my money fast lol.

FWIW,......

Most drag racing slick manufactures recommend a rim width that's 1" plus or minus whatever the tread width is.

I always try to error on the side of 1" wider,... rather than 1" narrow. Doing it this way allows for me to run lower pressures and the tire not have an uneasy (squirley) feeling going through the traps. Nor does the tire seem like it wants to wad up or fold over when using low psi's

My tires have a 13" tread width and I utilize a 14" wide wheel.

a 14" wide would have been my first choice, a smokin deal came up on these 15" wide rims so it is what it is lol. I dont have enough room in the tubs to go wider on tire, in fact these are gonna be a tight fit.

we switched to 15x14 dbl bead locks running 29.5x10.5 MT slicks. no cupping. of course that is with a 3400 lbs car with more air than most of you guys run.

What psi?

I keep reading that most of the big tire guys on here are in the 7.5-9 psi range. we are in the 11-12 psi range depending on the weight we have to carry that week.

11 is what I've been running.

cool deal. post some car pics up when you get that rear under the car.

will do, may be a couple months, Mike D works kinda slow lol.

It's too bad that beadlocks didn't get their start in drag racing long before they finally did. If they had an earlier start, by today their price could have been a lot lower & been more universally used by a lot more racers on a lot more cars.

Copperhead wrote:FWIW,......

Most drag racing slick manufactures recommend a rim width that's 1" plus or minus whatever the tread width is.

I always try to error on the side of 1" wider,... rather than 1" narrow. Doing it this way allows for me to run lower pressures and the tire not have an uneasy (squirley) feeling going through the traps. Nor does the tire seem like it wants to wad up or fold over when using low psi's

My tires have a 13" tread width and I utilize a 14" wide wheel.

X2..................

Did some mock up, man its tight in there but they fit lol. Honestly a 14" would have been my first choice but when a deal comes along you gotta make due. Seen many a 10.5 tire on a 14" rim, I did consider beadlocks but I couldn't justify spending way more for them over what the wheels cost lol.

I wish the tires set inside a bit further, but I'm not redoing the frame rails, tubs etc, this is a bolt in project which is not the norm for me, guess I'm getting lazy.

Wider rim is def better than narrow.

richter69 wrote: but I'm not redoing the frame rails, tubs etc, this is a bolt in project which is not the norm for me, guess I'm getting lazy.

Just wait till the dead of winter and you get cabin fever. You'll start hacking it up just to stay busy....