The tooth deflections caused by the transmitted load in spur gears results in a sooner start of contact (and a delayed end of contact) and a parabolic loading process (and downloading process) along the additional contact intervals. This increase of the effective length of contact reduces the interval of single tooth contact and therefore moves the critical load points, which influences the teeth strength. For spur gears with contact ratio close to 2 and heavy load, the increase on the length of contact may result in an effective contact ratio greater than 2. In this case, the interval of single tooth contact is eliminated, and the maximum load decreases, in such a way that the greater the total transmitted load, the smaller the fraction of the load transmitted by the teeth, which may result in lower values of the critical stresses. This paper presents a model for the determination of the load sharing ratio and the critical tooth root stress of spur gears with contact ratio greater than 2 under loading conditions.