305/30/19 on Front - Yep it's possible

[bracer]

I've always wanted to try this and finally got the chance with Apex Wheels blemish sale. Can't beat picking up wheels at 80% off list.

So for autocross I've always wanted more front tire grip. The issue is the hottest tire (RE71R) come in a 265 and a 305 in 19". In 18" there is a 285/30/18, and nothing wider.

So I've always wondered with enough camber if you could run 305/30/19 square like the Mustang's and Camaro's are doing.

So on a 19x10.5 ET22 it is possible, but it's very tight. You need close to stock ride height, and the fender liners need to be heated and contoured. They do clear all the important bits though. I believe I can autocross this setup without issue.

[F3IGHTY]

Nice work! Anything preventing a lower offset? Why is near stock ride height required?

[bracer]

Offset
There is about 5mm clearance to the strut so you could go a few more mm in, but that's it. On the outside you are fighting clearance when the wheels are turned so any lower offset will just make it worse. Clearing the outer fender isn't that hard actually. Ideal might be +24, but it's pretty close.

Perch Clearance
If I go any lower my spring perch would be in they way. I could probably go to 5" long springs and be fine though (Which I will probably try with a tender spring most likely).

[jacobe92]

Well done.

[CAOZKAN]

Originally Posted by blackey

I've always wanted to try this and finally got the chance with Apex Wheels blemish sale. Can't beat picking up wheels at 80% off list.

So for autocross I've always wanted more front tire grip. The issue is the hottest tire (RE71R) come in a 265 and a 305 in 19". In 18" there is a 285/30/18, and nothing wider.

So I've always wondered with enough camber if you could run 305/30/19 square like the Mustang's and Camaro's are doing.

So on a 19x10.5 ET22 it is possible, but it's very tight. You need close to stock ride height, and the fender liners need to be heated and contoured. They do clear all the important bits though. I believe I can autocross this setup without issue.

Are you on stock suspensions? I want to go with 295/30s on the front but it seems like I may have an issue with KW CS2s..

[F3IGHTY]

Originally Posted by blackey

Offset
There is about 5mm clearance to the strut so you could go a few more mm in, but that's it. On the outside you are fighting clearance when the wheels are turned so any lower offset will just make it worse. Clearing the outer fender isn't that hard actually. Ideal might be +24, but it's pretty close.

Perch Clearance
If I go any lower my spring perch would be in they way. I could probably go to 5" long springs and be fine though (Which I will probably try with a helper spring most likely).

Are you aiming for full lock to lock clearance?

Totally get it with spring clearance. 5" without helper seems like the ticket. But with this much tire it probably makes sense to go up in rate too. What are you at? I'm only at 550lbs/in right now.

[bracer]

I'm on MCS double's adjustable shocks. This is similar to stock as far as clearance goes. Anyone running helper springs, or anything with a spring longer than 6" is going to have an issue as you are going to need a spacer, and then I don't think you will have full turning capability.

Right now I'm running 600lb fronts. I really don't want to go stiffer than that for my street driving, so I'm going to start there. These actually give full lock to lock clearance. I have about 1/2" of clearance to the oil cooler / rear of wheel well.

[F3IGHTY]

Originally Posted by blackey

I'm on MCS double's adjustable shocks. This is similar to stock as far as clearance goes. Anyone running helper springs, or anything with a spring longer than 6" is going to have an issue as you are going to need a spacer, and they I don't think you will have full turning capability.

Right now I'm running 600lb fronts. I really don't want to go stiffer than that for my street driving, so I'm going to start there. These actually give full lock to lock clearance. I have about 1/2" of clearance to the oil cooler / rear of wheel well.

Awesome, appreciate the details - thanks for pioneering

[The Choosey begger]

Nice!

[espressoo]

Originally Posted by blackey

Offset
There is about 5mm clearance to the strut so you could go a few more mm in, but that's it. On the outside you are fighting clearance when the wheels are turned so any lower offset will just make it worse. Clearing the outer fender isn't that hard actually. Ideal might be +24, but it's pretty close.

Perch Clearance
If I go any lower my spring perch would be in they way. I could probably go to 5" long springs and be fine though (Which I will probably try with a tender spring most likely).

Do you account for tire flexing and etc while cornering? That looks awfully close.

[uniqueMR]

[The Choosey begger]

Originally Posted by espressoo

Do you account for tire flexing and etc while cornering? That looks awfully close.

I think a 6" spring at stock height will fix that.

[bracer]

Moving to a 5" spring will give more room, but the perch is actually above the tire. It's just an optical allusion that it's that close. Unless the tire grows in diameter it should be ok.

[adc]

Aren’t you concerned that you’re eliminating the tire *diameter* stagger front to rear? There is a school of thought, which my shop subscribes to, that you need the diameter stagger at higher speeds or else it will confuse the electronics.

Another question is how much camber are you running?

[bracer]

I don't run any of the electronics when autocrossing or tracking. I've found I'm faster without, so I really don't need to worry about that, YRMV. ABS doesn't seem to care. I run equal size tires (Slicks) on the track and the ABS is fine for that.

[nicknaz]

wow. nice work.

Would you use it for HDPE too? curious to hear more about how the fit is when you really load it up in high speed corners

[bracer]

bumping this forward as someone asked if it's possible.

[erictrainer]

Originally Posted by blackey

bumping this forward as someone asked if it's possible.

Thanks for reposting... great research!

blackey So do you ride this setup square?

[MPOOR]

Nice Fitment ~!!! Looks DOPE ~!
Just curious, how did the steering feel change with 305 Front.

[FTP20]

Originally Posted by blackey

So I've always wondered with enough camber if you could run 305/30/19 square like the Mustang's and Camaro's are doing.

So on a 19x10.5 ET22 it is possible, but it's very tight. You need close to stock ride height, and the fender liners need to be heated and contoured. They do clear all the important bits though. I believe I can autocross this setup without issue.

Thanks for doing the homework on this! I want to run Mich PS4S 295/30R19 fronts on custom wheels, probably 19x10.5" ET22 or ET24. How much negative camber does your car have up front?

[bracer]

Steering feel was about the same, maybe a bit more effort, but I was running 275's already.

Mine has -2 on the street and about -3.25 on the track

[Lienrocs]

Bumping this back up, OP.

Any updates on the 305 fitment? Is there enough room to be able to get more tire in the rear?