5th wheel rotation for HPDE track days - slightly different wheel ok?

New to the forum - looking for opinions/wisdom on this please:

I have a set of 4 relatively inexpensive Sport Tuning wheels I bought from Tirerack with Falken AZENIS RT615K+ tires.  I use them exclusively on the track and have another set of OEM wheels for the street.

I'm thinking of buying a 5th wheel and matching tire to have a spare for the track, so I can rotate for wear more effectively, and so if I damage one it doesn't ruin an entire day or event.  I figure the cost of the spare tire/wheel is about the cost of the entry fee for one day, so well worth it.

Anyway, the problem is that Tirerack no longer carries the exact wheel to match.  I can't find a matching one to purchase anywhere.  Tirerack does have a very similar wheel I'm thinking of getting.  The visual design is slightly different, which doesn't bother me at all.  The specs are almost identical, except the one they have is 0.4 lbs lighter. 

So the question is - would racing with 1 mismatched wheel be a safety/performance issue?  Again, the wheels are as identical as they could be, except that one wheel is 0.4 lbs lighter - which is only 6.4 ounces.  Of course, the reps at Tirerack can't advise me that it would be a good idea, but I understand they have legal and other reasons to be extremely careful when advising me. 

So what do you think?  Thanks in advance!

Details: The size, offset, bolt pattern, etc are all identical.

I'm thinking of buying one: Sport Tuning ST4 machined w/ black accent - ST4880455112BMF
Weight: 24.3 lbs.

I already have four: Sport Tuning ST1 machined w/ black accent - ST1880455112BMF
Weight: 24.7 lbs.

Width and offset the same? You good.

fatallightning said:

Width and offset the same? You good.

Yup.  We run mismatched wheels on our lemons car all the time, but they are matched on the axle for width/offset/size.  Never any issues in years. 

Width, offset and tire size the same- go for it. Whatever wheels you run, they should be inspected for cracks and wear every time you install them. They have a finite service life. 

Thanks for the input all!

Am I the only guy who read the title, and immediately wondered why is he tracking one of these?

In reply to Appleseed :

Ha!  I came across that multiple times when trying to google for an answer also.

Thanks everyone for the input - I ended up ordering it.