10.9 suggests metric threads. 10.9 seems to be a fairly unusual standard in industrial fasteners IME (though it seems more common in automotive fasteners): if something stronger than 8.8 is needed, it has been normal to go straight to 12.9 IME.
Running a die down a 10.9 fastener will completely negate the 10.9 designation: the only reason I can see for using ARP, or similar, premium hardware, is the expectation of better fatigue performance/life and you'll certainly lose that with the die.
ARP hardware is pretty high-end and rather spendy, as far as I can tell. I'd expect any reputable brand (Unbrako, Holokrome, etc) of High-Tensile industrial fastener to get the job done, particularly given that there's much less of a fatigue issue in your application than in an engine where ARP fasteners might make economic sense: you are talking in terms of 1000 stress cycles/year. That's only about 10-seconds-worth of stress cycles on a 6000 RPM engine.
Could you use 12.9 socket-head cap screws and decent (preferably hardened) washers?
I'd not expect steering wheels to use much over M6, perhaps M8, fasteners. At work, we use M8 and M10 SHCS to attach bearing puller plates for removing blower bearings and consider them expendable, as the cost of the screws is negligible compared to the bearings,
The 12.9 SHCS tend to be pretty cheap (a box of 200 M6 x 50 12.9 SHCS costs about the same as a decent M6 die here in the UK). Alternatively DIN 6921 hex flange bolts in 10.9 or 12.9 grade?
You'll still be best served replacing them as soon as things feel at all suspect, but the sticker shock is likely to be dramatically reduced.
For those unused to the metric designation, the first number, before the decimal point/full stop, refers to the Ultimate Tensile Strength (in hundreds of MPa) and the second number refers to the Yield Point as a proportion of the UTS.
A 10.9 metric fastener has an Ultimate Tensile Stress of 1000 MPa and a Yield stress 90% of the UTS. That translates to 145,000 PSI UTS and 130,000 PSI yield.
A 12.9 metric fastener has an Ultimate Tensile Stress of 1200 MPa and a Yield stress 90% of the UTS: 174,000 PSI UTS and 156,000 PSI yield.
As a comparison, a Grade 8 SAE fastener has an Ultimate Tensile Stress of 150,00 PSI and a Yield stress of around 130,000 PSI (Proof load is 120,000 PSI, which is the minimum load it can withstand without permanent deformation (yield)).
The ARP website does mention that they manufacture in some higher-spec materials for racing, etc, but you are "only" using the 10.9 fasteners: ARP's "vanilla" grade.
