Five year old article on the "15 inch tire problem"
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Honestly for anything high effort, you go 18s because the tie rod fits inside the wheel.
You are certainly right that the biggest possible tires are available when you get to 18” diameter wheels.
@72bluNblu and a handful of you guys have demonstrated that with impressive results. I’ve toyed with the idea of following this path, even strongly considering my own set of RPF1s inspired by Brian’s amazing Duster/Demon. It just never quite felt right to me for my vision.
I guess when it comes down to it, I’m willing to not be absolutely optimized in terms of contact patch. Of course I want a good wide tire but so long as it’s a legitimate performance tire with a sticky compound, I don’t believe the extra 15mm of rubber would make that much difference to the driving experience. In fact, the extra steering effort and tramlining with ~295s would exacerbate the unlovable characteristics of my 16:1 manual box and 5 degrees of caster combo.
So, to me the extra grip isn’t quite worth the extra weight, extra cost, extra mods, drivability penalties…and aesthetics that push the car even farther from my vision.
Also, my performance bottlenecks will almost certainly be steering and chassis related at this point. The car has upgraded torsion bars, control arms, springs, etc. it also torque boxes and subframe connectors but it’s not caged. That extra grip is just going to push against other built in limits that I have yet to address.
As for 17” fitment issues, from what I gather from 72Blu and others, 17x8” wheels typically don’t have tie rod interference issues if you are at 5.5” backspace or less. Of course the less backspace, the skinnier tires (since fender clearance becomes a problem). So if one was satisfied with 245s, there shouldn’t be much trouble fitting wheels to accommodate this. Corrections are welcome but I’m pretty sure about that.
