The ins and outs of racing in the rain

If the class still goes out when the track is wet, the deciding factor is whether you have already driven with the kart moving under you, not whether rain running will polish your dry throttle. Once the throttle is already under control, extra wet laps do little for dry lap time. Those laps still teach you how early the rear starts to walk and where standing water kills traction, which is what you actually need on a wet race day. Skip that work and you give away positions to anyone who has already been out in those conditions. After a wet session, pack both hubs before the kart sits or it will pull like a setup problem the next dry day. The chain and brakes take water as well. Leave rinsing the frame until that is done. Extra workshop time only pays when you actually fit the rain set; unused rain rubber still ages on the shelf.

The idea that wet running automatically makes you smoother on a dry day is mostly a category error. Rain lowers available friction and makes it speed-dependent, because a water film can support the tire instead of the rubber itself. Staying inside that smaller, moving limit teaches delayed force buildup and patchy surface reading, which is useful, but it is not the same task as placing a dry slick at a high and relatively stable friction coefficient. If throttle discipline is already there, the transfer is limited. The grooves in a rain tire exist to evacuate water so the contact patch can shear against asphalt rather than ride on a lubricant film. Water in a wheel bearing displaces grease and raises rolling resistance, and if that is uneven left to right the kart yaws like a dragging brake, which is why packing them after a wet day is not optional. That maintenance cost is real, but it does not substitute for the tire.