Steering Wheel Size

[7uptruckracer]

I know this may seem like a dumb question but when you think about it, it makes a big difference. I know most chassis builders call for a specific rack and servo. What size wheel are they basing this off? a 15" or 17"? or what? We first got a racecar and didn't realize at first someone had sold it with a 13" wheel and after I got it in realized why the owner was so darty in it it was way to quick steering, So we went to a 15" and it helped a ton! Just wondering if we can help him anymore with a 17"! What do most of you guys run and if you wanna explain your thinking we would more then love to hear it. Side note he is of a sprint car background! He can drive just trying to give him something that he can win with!

[MasterSbilt_Racer]

Use what the driver likes. That is all that matters. I prefer a big wheel myself.

[hpmaster]

With a standard servo I liked the 17" wheel. Now that I am older than dirt I use an extra light servo and a 15" wheel, mostly for belly clearance, LOL.:p

[rubbinsracin]

x2

im 285ish lbs and have a...shall we say..."Santa-Like" belly. no bigger than a 15" for me. with a 17" i would be up against my belly/belts

[7uptruckracer]

It's the rack for the black front end rocket with the rack ratio for that and standard servo

[AmickRacing]

I started off with a 17" (and a dang slow rack too), upgraded to a 15" (same slow rack) and it was much better.

Now I'm running a normal rack (3.25 I believe) with a 15" wheel and it seems to work fine for me. Some people like the larger wheel for being smoother, I find I can be just as erratic with a big or small one :eek:
I've also got a decent bit of upper body strength so I don't need much extra leverage to keep the wheels in the general direction of where they need to go.
I also have th slight clearance problem with the larger wheel lately too.

[jedclampit]

Key points to remember is wheel size affects steering effort, hands/arm travel and of course belly clearance, it does not change ratio.

My advice ......use the biggest wheel your belly will allow.:o

[Egoracing]

I know people that use a 17 in a rough track and a 15 on a smooth one. Helps with the bumps and ruts. I would agree on the largest that you can use.

[zerolm]

Ego, you are correct that wheel size does not technically change the steering ratio. However, to turn a steering column 90 degrees with a 17" wheel, you have to move your hands 8 1/2" (I'm using the figure as if your hand moves straight for purposes of making the math easy). To move a steering column 90 degrees with a 15" wheel, you only have to move your hands 7 1/2". Because of this, when measuring how much wheel movement by distance, you have to move your hands less distance to acheive the same angle on the front tires. Therefore meaning the ratio between your hands to angle at the wheel is acutally "quicker" with a smaller wheel.

[dfhotlm33c]

Nice reply zero...nice to see someone throw some math in there! (I have a master's in math, but wish to heck now that I'm racing that I had one in engineering too!)Think of it like gear ratios on your rear end..if you put bigger tires on, you certainly don't actually change the gear ratio in the rear, but you do change the "effective" gear ratio seen by the tire at the road..