Why would you drag a tire during a rollerski race?

So why would you drag a tire during a rollerski race?

Race Director Andy Liebner told participants in the Grand Rapids 10k Rollerski Race on Sunday, November 5 that dragging a tire "reduces roller ski wheel speed advantages and increases safety of use on the bike path". I can think of some alternative reasons:

Promotes ankle lean and good technique
Increases strength
Looks cool!

Racers attached a tire (or half tire) via a bungee cord attached to their drink belt. Time bonuses were given based on weight of tire: the heavier the tire, the better the time bonus. Time bonuses were calculated as ((Tire Weight / .25) * (30 seconds)) / 60 seconds. Liebner provided the tires and bungee cords.

Grand Rapids roller ski race, pulling a tire 11

Half tires used for the race. Full tires have too much resistance. (All photos: Thierry Werderits)

Starting at 30 second intervals, racers skied a 10k course through Millennial Park in Grand Rapids, Michigan under wet conditions. Grand Rapids Nordic Ski Team's Steve Smigiel Jr finished with both the fastest time (40:16) and fastest time adjusted for tire weight (24:46). Eric Parot and Ricardo Lung were second and third overall with close times of 26:43 and 26:46.

Grand Rapids Rollerski Race Results

Place	Name	Tire Weight	Bonus Time	Start Time	Finish Time	Total Time	Adjusted Time
1	Steve Smigiel Jr	7.75	15:30	2:30	42:46	40:16	24:46
2	Eric Parot	9	18:00	3:00	47:43	44:43	26:43
3	Ricardo Lung	10	20:00	3:30	50:16	46:46	26:46
4	Greg Worsnop*	7.5	20:00	4:30	51:47	47:17	27:17
5	Don Camp*	9.25	23:30	1:00	53:37	52:37	29:07
6	Jim Beebe	6.5	13:00	4:00	46:30	42:30	29:30
7	Skip Schott	5.5	11:00	2:00	47:42	45:42	34:42
8	Chris Anderson	9	18:00	1:30	59:31	58:01	40:01
9	Dan Nolan	0	0	5:30	46:13	40:43	40:43
10	Steve Smigiel Sr	6.25	12:30	0	53:14	53:14	40:44
11	Spencer Ruffner	7.5	15:00	:30	60:33	60:03	45:03
12	Peter Johnson	6.25	12:30	5:00	67:42	62:42	49:12