So I've been reading on spare tire setups people are trying out for the stock car with BBP, and have been wondering something.

The stock wheels 255/40/19 are 27" tall all around. If I place a spare that's 27" tall anywhere we're alright. Now lets say I have a 26" spare and get a blowout on a rear tire. If I place a 26" spare on one side, and a 27" on the other side, won't that cause the differential to turn at different speeds...causing something to break very quickly, and very violently?

Also, in concerns with ABS being tripped. If you're running larger rear tires than front tires, will the ABS see the rotational difference of the slower turning rear tires and get tripped? A GT has 4 equal sized tires, but the GT500 SVTPP has 2 different ones. 265/40/19 27.4" front and 285/35/20 27.9" rears. This would lead me to believe there is a threshold that must be surpassed causing it to kick in, and 0.5" isn't enough. Now...is it programmed into the GT500 or is it a physical difference in the way the car is made, aka wheels wont work on a GT.

Now let's excacerbate the problem with 255/35/20 27" fronts and 305/35/20 28.4" rears. Is 1.4" enough to cause problems?

The next set of tires I was going to go with were NT05 275/35/20 27.6" front and 315/35/20 28.7" rears which is only a 1.1" difference.

 

lol, seriously, no one knows. Nice.

 

I read it but I don't understand the question.
You can only use different size rear wheels to like .5 inch diameter difference with track-lok. That has been discussed ad naseum concerning Fords failure at providing spares and/or correct size spares.
And you must turn traction control off to avoid the abs reacting.
Other than that, I don't know what info you are seeking.

 

Thanks, I'll try researching that now.

 

Years ago a friend had 2 different size tires but the rims were the same and it screwed up his 4 wheel drive Nissian. It wouldn't go into 4WD for love or money. After he changed the tires it worked great.