Hi techbike-

out of curiousity- you can ask the tech to balance the wheel on the machine without a wheel on it and see the balance specs on the wheel(s) themselves...they may try and rotate the tire mounting position on the rim also to try to cure this condition

often +1, +2 tire, +3 larger tire/wheel upgrades have downside characteristics (esp if the suspension, chassis, steering wasn't engineered w/ this upsized equip in mind) and,...there'a more stress and wear on these parts with the plus sizing

-fad