Tire Sizes Question

[vblkwng]

I am looking for a drag tire, and was wondering if anyone has been able to fit a 305/35R19 on their car? I found a few tires, but it looks like the 35's are about 1.21in taller, which is going to require clearance of about 3/4in above the tire more.

 

[sleepys4]

yes they will fit.

There is a plenty of room for that size. Could go 315/35/19 with no problem as well.

 

[BlueBird]

yes they will fit.

There is a plenty of room for that size. Could go 315/35/19 with no problem as well.

I had read that the OEM tires are pretty maxxed out already. The OEM Michelins even remove the lip protector on the inside of the tire to get clearance. I'd love to know if more tire can be stuffed in there but I'd need to see it.

The Drive - Blackwing Wheel and Tire Article

"Grebovic drew special attention to the 305-section rears on the CT5-V Blackwing. If you look closely, the tire has a slightly raised rim protector—about as wide as something you could rest the tip of your fingernail on—that's designed to protect the rim in case the driver hits a curb. Just to have those tires fit correctly on the car, "We actually had to get rid of this on the inside to package the tires," he said. "There is no room in there. So when I say we shoved as much tire as we could in there, I mean we took [the rim protector] off just to gain another two or three millimeters. This was to make sure we could get the performance we wanted out of the suspension and the chassis.""

 

[MatthewAMEL]

That article caused me some concern as well. Turns out it just isn't true. A 285/30-19 fits up front with no issues.

Apex also confirms that a 20" wheel fits with no clearance issues. So you can run the whole range of 285/305-20 tires that are avail. That's a lot of good tires.

 

[BlueBird]

That article caused me some concern as well. Turns out it just isn't true. A 285/30-19 fits up front with no issues.

Apex also confirms that a 20" wheel fits with no clearance issues. So you can run the whole range of 285/305-20 tires that are avail. That's a lot of good tires.

I am gonna muddy the waters, but the Apex fitment guide shows their staff pick tire for the front as a 275 for 19" wheels and they suggest camber changes for the 20" wheel and tire packages (I assume to clear fenders but don't know for sure).

 

[MatthewAMEL]

I am gonna muddy the waters, but the Apex fitment guide shows their staff pick tire for the front as a 275 for 19" wheels and they suggest camber changes for the 20" wheel and tire packages (I assume to clear fenders but don't know for sure).

Not quite...sometimes the fitment guides can be a little hard to read.

Wheels

• Front: 19x10" ET20 // Rear: 19x11” ET44
  • Available in: SM-10, VS-5RS
  • 3mm rear spacer needed with carbon brake cars
  • Compatible with factory tires

Tires

• APEX Staff Pick: Front 275/35-19 // Rear 305/30-19
• Max Performance Summer: Michelin Pilot Sport 4S (300TW), Continental Extreme Sport 02 (340TW)
• Extreme Performance Summer: Falken RT660 (200TW), Hankook RS4 (200TW), Michelin Sport Cup2 (180TW), Kumho V730 (200TW)
• R-Compound: Nitto NT01 (100TW), Toyo R888R (100TW), Nankang AR-1 (100TW)

Wheels

• Front: 20x10.5" ET15 // Rear: 20x11.5” ET42
  • Available in: VS-5RS
  • A minimum of -1.5º front and -1º rear camber suggested
  • No spacers required
  • Not recommended for lowered cars due to additional tire height

Tires

• APEX Staff Pick: Front 285/30-20 // Rear 305/30-20
• Max Performance Summer: Michelin Pilot Sport 4S (300TW), Continental Extreme Sport 02 (340TW)
• Extreme Performance Summer: Goodyear Supercar 3 (220TW), Michelin Cup2 Connect (240TW)
• R-Compound: Michelin Cup2 (180TW), Goodyear Supercar 3R (100TW)

 

[BlueBird]

Sorry but I still don't see it? For 19" wheels I see they have 275 as the front tire.

Here's what Wheelsize.com's calculator says when swapping from Apex's 19" 275 front wheel fitment to the 20" 285 fitment:
"Suspension clearance: The Same"

But here's what happens on a 19" when you size up to a 285:
"Tire is 5 mm closer to suspension components"

 

[vblkwng]

yes they will fit.

There is a plenty of room for that size. Could go 315/35/19 with no problem as well.

Have you done this already then?

 

[MatthewAMEL]

Sorry but I still don't see it? For 19" wheels I see they have 275 as the front tire.

Here's what Wheelsize.com's calculator says when swapping from Apex's 19" 275 front wheel fitment to the 20" 285 fitment:
"Suspension clearance: The Same"

But here's what happens on a 19" when you size up to a 285:
"Tire is 5 mm closer to suspension components"

I'm not sure what you are confused by...

Apex staff picks account for everything the end user might consider when choosing a wheel size. They stuck with the 275 on 19" simply because there are more/better tire choices in that size than a 285 19". Not due to fitment.

That's why the step up to a 285 on the 20" because of the types of tires avail in that size.

And the camber you mention is less than the street spec. If you set to track spec, you run -2.5F and -1.5R.

Don't forget, the V Team picked a tire that had good track performance, but still delivered the 'Cadillac experience' when in tour mode. The PS4S TPC is an excellent jack-of-all-trades tire, but it's NOT the last word in tire for the Blackwing. The fact that they picked a -35 profile tire with acoustic foam shows you they are doing their best to straddle the fence.

 

[BlueBird]

I'm not sure what you are confused by...

Apex staff picks account for everything the end user might consider when choosing a wheel size. They stuck with the 275 on 19" simply because there are more/better tire choices in that size than a 285 19". Not due to fitment.

That's why the step up to a 285 on the 20" because of the types of tires avail in that size.

And the camber you mention is less than the street spec. If you set to track spec, you run -2.5F and -1.5R.

Don't forget, the V Team picked a tire that had good track performance, but still delivered the 'Cadillac experience' when in tour mode. The PS4S TPC is an excellent jack-of-all-trades tire, but it's NOT the last word in tire for the Blackwing. The fact that they picked a -35 profile tire with acoustic foam shows you they are doing their best to straddle the fence.

I just figured that the choice to step up to 285 on the 20" setup would be due to the wheel being 10.5" wide with a 15mm offset, vs the 10" wide, 20mm offset 19" setup.

Either way, Apex doesn't say in their guide why they picked a 275 for their 19" wheel vs a 285, and the camber for the 20" is what they suggested per the guide and not my numbers.

Personally, I'd need to see that a 285/35r19 on a 19x10 ET20 would clear the suspension under compression before I'd put one on. The math says I'd be placing a tire that's 4mm taller, 5mm closer to the suspension components. It looked tight when I looked in there, although I didn't measure.

And as for a 315/35r19...that's nearly 20mm taller and 5mm closer to suspension components in the rear so break out a tape measure I guess.

I'm as interested to see what tire options start being used as anyone, but I need to see it to believe it.

YMMV

 

[MatthewAMEL]

Either way, Apex doesn't say in their guide why they picked a 275 for their 19" wheel vs a 285, and the camber for the 20" is what they suggested per the guide and not my numbers.

Personally, I'd need to see that a 285/35r19 on a 19x10 ET20 would clear the suspension under compression before I'd put one on. The math says I'd be placing a tire that's 4mm taller, 5mm closer to the suspension components. It looked tight when I looked in there, although I didn't measure.

I explained why Apex is suggesting the OEM tire size with their 19" wheel. More choices in tire. Retains OEM tire fitment.

No one suggested a 285/35-19. I specifically suggested a 285/30-19. A 35 sidewall makes steering inputs mushy, but ride quality better.

You do realize the Apex 19" front wheel is OEM sized, right? 19x10ET20 is OEM. So the math is the same as OEM. The -30 tire is SHORTER than OEM.

As for the camber suggestion, you are already running MORE than Apex's suggested camber settings with just the street alignment the cars ship with. Apex is geared for performance driving. Vast majority of their products are used on the track. If you track the Blackwing, you are running FAR more camber than they suggest. The Owners Manual has the track specs at -2.5F and -1.5R...no fitment issues with the 20".

It's still early in the game for wheels/tires on this platform. As people experiment (and hopefully share) we will learn what works and what doesn't. I will be running a set of Signature SV501 in OEM size for AutoX and the 20" Apex for Track.

 

[BlueBird]

Apex staff picks account for everything the end user might consider when choosing a wheel size. They stuck with the 275 on 19" simply because there are more/better tire choices in that size than a 285 19". Not due to fitment.

I explained why Apex is suggesting the OEM tire size with their 19" wheel. More choices in tire. Retains OEM tire fitment.

It makes sense to provide more tire choice but, and I mean no offense by this, you stating that it was not due to fitment does not make it factual. Until I know that you work for Apex or have it in writing, I can only take this as an opinion, since it isn't presented as a fact by Apex. Nothing personal.

No one suggested a 285/35-19. I specifically suggested a 285/30-19. A 35 sidewall makes steering inputs mushy, but ride quality better.

You are right! I was mistaken when referencing your suggestion. Sorry!

You do realize the Apex 19" front wheel is OEM sized, right? 19x10ET20 is OEM. So the math is the same as OEM. The -30 tire is SHORTER than OEM.

Yes, I know that the wheel is OEM sized, but a 285/30r19 is -21mm smaller in diameter (I do not get -30?) from a stock 275/35r19 tire. That means it is -10.5 mm reduced in height away from the struts (10.5mm shorter sidewall/-21 mm in diameter) but still pushed inboard 5mm towards the suspension.

Based on that information, I'd still need to know what remaining inboard clearance/distance between my tires and struts when under load, because I'm still losing 5mm between the tire and suspension when running a 285/30r19.

I'm not saying that it won't fit, I am however saying that without data I can't agree that it will, so buyer beware.

If my data is wrong, I want to know. I love learning car stuff

Alternatively...use a spacer if needed....lol!

 

[Tall Steve]

 

[GTANotch88]

I'm also interested in finding a good drag tire.
What fits the front, or in a 20" size is irrelevant.
I want a drag radial that will fit a stock wheel.

The MT ET Street S/S looks nice but the 305/35/19 size is 27.20" diameter.
The Michelin Pilot Sport 4 S tpc is 26.30"
So only about a .90" difference, and less than .5" more clearance needed.

The MT ET Street S/S in size 285/35/19 is 26.90" so that might be an option.

(Measurements are from Summit Racing and Michelin.com)

 

[vblkwng]

I'm also interested in finding a good drag tire.
What fits the front, or in a 20" size is irrelevant.
I want a drag radial that will fit a stock wheel.

The MT ET Street S/S looks nice but the 305/35/19 size is 27.20" diameter.
The Michelin Pilot Sport 4 S tpc is 26.30"
So only about a .90" difference, and less than .5" more clearance needed.

The MT ET Street S/S in size 285/35/19 is 26.90" so that might be an option.

(Measurements are from Summit Racing and Michelin.com)

I might need to be the guinea pig and try out that 305/35/19 this year.

 

[MDM]

I'm right there with you! It's between the MT and the Nitto. Nitto has a matching tire you can get for the front. The 5 BW 6-spd definitely needs more traction in first and second. I'm a few weeks from making the switch.

 

[vblkwng]

I'm right there with you! It's between the MT and the Nitto. Nitto has a matching tire you can get for the front. The 5 BW 6-spd definitely needs more traction in first and second. I'm a few weeks from making the switch.

I could care less about the front, at most I'd go smaller.

 

[GTANotch88]

Bringing this back...

I found these on SummitRacing.
Personally I never heard of this company so I dont know anything about them.

Atturo Tires Drag Radial
305/30-R19
They have a listed diameter of 26.26(stock tires are 26.3)
390.00 each

Atturo Tires DR850-D3JN9ATA Atturo AZ 850 DR Tires | Summit Racing

Free Shipping - Atturo AZ 850 DR Tires with qualifying orders of $109. Shop Tires at Summit Racing.

www.summitracing.com