Measuring for fat front wheels?

[miketyler]

Any ideas on best method of measuring backspacing and overall fitment for new front wheels? The rear is pretty straight forward running a 315/35-17 on the stock 17x11 wheel with 7"BS. I don't like spacers but may need to run 1/4"+ for needed spring clearance.

What about fronts? They are a different monkey however and will be more of a challenge with my target combo of 275/40-17 tire wrapped around a 17x9.5 wheel. Closest stock BS is 6.375" which is too much. Others running 17" on front with 245/50 run anywhere from 4.5"-5.25" BS. Once you order custom BS wheels they are yours. What's the best way to measure this - put the tire in the well with weight on the suspension and measure in different positions? Maybe get a similar bare wheel and bolt on and measure clearances or ? Maybe all of the above?

         

[HP2]

Well, XV has put 275 in the front of a Challenger, so it is physically possible. Nailing down the back spacing and the potential interference with suspension points may be the biggest obstacle.

Short of disassembling your suspension to mock up a wheel size and cycle the suspension to check for interference, you have to make some calculated estimates. Check you current tire size and wheel spacing for potential interference areas, take copious notes about these clearances, then add the new dimension of the desire wheel/tire combo to see what issues you may run into. You can check with these guys for spacers/adapters if necessary; http://www.wheeladapter.com/home.asp

[miketyler]

Cool - sounds like I'm on the right track then. The size of the tire/wheel combo you intend to fit will dictate your margin of error. Something this big puts you in the closer tolerance than say a more conventional size.  In the end you can do all the measuring and think you have all the bases covered only to find the finished assembly catchs the lower forward fender well.   

Thanks for the response! 

[HP2]

Yes, that is true which is why mocking up and cycling the suspension is the best answer. If you getting into a suspension rebuild at the same time, then it is easy. If not then it requires you remove the shock and t-bar to get the full range of motion to check fit. Your alignment specs can also have an impact on this as well as large increases in positive caster are going to position the wheel in a different space than negative caster not only while sitting but also through the range of motion. Changes in camber gain and strut rod bushing compression also are factors. Interference with the strut rod and upper control arm are also big factors on a stock suspended car.

[gkring]

http://store.summitracing.com/partdetail.asp?autofilter=1&part=PHP%2D01201&N=700+115&autoview=sku

I bought one of these awhile back, with the intentions of doing what you are doing when I get to that point.
I have no idea how well it works, but you can borrow it if you want. I'm in Arlington, not too far from you.

[miketyler]

Thanks Greg - is was great meeting you and drooling over your vert in the rotisserie! Will get the wheel sizer back to you asap!