For a polyisobutylene/decalin solution “D2b,” agreement over a range of values of shear rate γ̇ up to29,000 s−1(where the stress ratioN1/σ=5;σ=shear stress) is found between values ofN1measured near 20°C using a Torsional Balance Rheometer (“TBR”) and a “Stressmeter” (“SM”, a slit‐die rheometer using transverse slots to measure hole pressures); viscosity values also agree. Time‐temperature superposition behavior exhibited by SM data taken in a temperature range 22–99°C suggest that the range of validity of the SM method for determiningN1approximately extends up toγ̇=1.3×106 s−1;here,N1/σ=10and, in the SM die, the Reynolds numberRe=100.This γ̇ value is four times higher than the greatest γ̇ value used in previous similar tests of the SM method made with a similar but more concentrated solution “D2”.