I'm just copying and pasting from Tire Rack's website. Their measurements show the 295/30R18 having 10.3" tread width, which is consistent with what you're seeing.

 

I know but I'm disagreeing that Tirerack actually measures them. Assuming Continental's numbers are accurate, 200TW tires tend to be wider than what is on the spec sheet
I can fit 315 ECS02 if it was available. I'm not too happy with the stretch with these 295s

 

They actually do. There's a Tire Rack employee on another forum who talked more about the process. He's even gone back and re-mounted and re-measured a couple tire/wheel combos when people complained that the numbers didn't look right.

EDIT: https://www.tirerack.com/upgrade-gar...re-tread-width

 

I guess what youre saying is TR cant do anything to change whats printed on the sidewall, but they provide "more info" ?
I was just not expecting the huge diff having the same "tire size"




https://www.tirerack.com/upgrade-gar...flWYJTsjokj9Gs

 

Tire size on the sidewall is nominal. You can have large variations even in the same tire from manufacturer if they make a different bespoke tire for a few different OEM's. Certain size michelin pilotnsports vary as much as an inch (even though theyre the same "size") depending if its for Merc, BMW, Ferrari, etc..

 

Thanks guys. This is my first time buying "regular tires" lol. dangit I should have kept my 10.5" NT03s

 

The sidewall number is Section Width, but most of us care about Tread Width.

Tread width is a hard number to pin down because the shoulders of tires are rounded. That's why Tire Rack has their angled measuring jig to get a reasonable estimate.

The NASA series set their own specifications for measuring tire size with a set of simple tools with a rectangular cutout. If you can fit the tool over the tire, you can run it. Doesn't matter what it says on the side.

Great for leveling the playing field, but frustrating when you get your tires mounted up and they're just a couple mm too wide.

 

With the release of vitour p1 there are now super wide 15 inch tires for autocross. What do we think about 305/30r15s on some 15x11s with a 4.0 final gear swap for an autocross only car (XA)?

 

need brakes for 15" wheel too. thats a lot of "upgrades" just to get the extra thread width

 

its more about dropping 10-15 lb from each corner, which the smaller brakes would also help with

Edit: people been running 305s etc but instead of a 17 or 18 inch rim if you can do it on a 15 inch and then make up for the smaller diameter with a lower final drive you can
1. save a bunch of rotating mass
2. lower the cg without any detriment to suspension geometry

I cant think of the downsides other than cost to do final drive and brakes but you will get some of that back in cheaper wheels and tires

just an idea and wanted to see what people thought. I am building a new autocross car to replace my swapped brz so am brainstorming some out of the box stuff for it

 

that sounds like an FP Evo moving to XA. yeah you can build any car you want. I'm on the side of the spectrum where I want an arrive and drive street car or have a F&F C&C hard parker in just for the action pics IMO the car should look like its setup up for "Ultimate Street Car" which can do track and autox
If i have a strong desire to be on top, i'd just buy a shell evo and cut the fenders and run proven tires. BTW you'll need something for cold/wet days

 

thats what my brz is. More built for ultimate street car than pure race, bunch of unique one of kind stuff (only gen v lt swap in the world, side pipes etc). But I am building this evo from the ground up to be the most competitive autocross car I can think of (with 200tw tires) at least that is the current plan, I’m just starting the build now so we will see where it goes. And I don’t do proven stuff haha, I always push the envelopes with my builds (can’t help myself unfortunately, would be a lot easier if I just bought parts and bolted them on)

 

well the P1s were proven to suck for autox
hope to see you in Lincoln.

 

lol

 

Yeah. P1 is not a good autocross tires. Needs good temp.