285 vs 315
Burning Brakes
Joined: May 2009
Posts: 1,178
Likes: 224
From: Austin Texas
What kind of rwhp are you making?
Last edited by C6-LS2-MN6; Nov 4, 2015 at 10:08 PM.
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
There is a little bit of a diminishing return if you just go by increase in width since the weight of the vehicle remains nearly the same so the contact pressure per square inch of tire is reduced as you go wider. However on a well prepped surface there will be a benefit to this increase in width and if you can fit them why leave any performance on the table?
Thread Starter
Cruising
Joined: Nov 2015
Posts: 12
Likes: 0
Team Owner
Joined: Sep 2001
Posts: 23,283
Likes: 906
From: Lake Elsinore, CA
Got a set of Michelin PSS 295/30/20's for the rear of my Z51 today. 295 is the widest recommended tire width for a 10" wheel. I will probably go one size wider on the fronts when i replace those as well. I'd like to go with a 305 on the rear but not willing to risk rubbing.
Burning Brakes
Joined: May 2009
Posts: 1,178
Likes: 224
From: Austin Texas
Custom made 360 Forged wheels on mine with 305 in rear. 305s are the max you can fit on a c7. 315s will slightly rub.
LINK:
https://www.corvetteforum.com/forums...-c7-pic-s.html
LINK:
https://www.corvetteforum.com/forums...-c7-pic-s.html
Last edited by C6-LS2-MN6; Nov 5, 2015 at 12:54 AM.
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Burning Brakes
Joined: Sep 2011
Posts: 960
Likes: 40
It's the tall 315/30-20 that can be a problem on the C7. A 315/30-19 is okay at 75mm to 79mm rear wheel offset. The short 315/30-18 is often stuck out the rear fender.
315/30-20, R888, 27.6" diameter
315/30-19, Pilot Sport Cup 2, 26.5" diameter
315/30-18, R888 and Rival S, 25.5" diameter
.
315/30-20, R888, 27.6" diameter
315/30-19, Pilot Sport Cup 2, 26.5" diameter
315/30-18, R888 and Rival S, 25.5" diameter
.
Last edited by B Stead; Nov 5, 2015 at 04:09 AM.
Racer
Joined: Apr 2014
Posts: 373
Likes: 10
From: Rye New York
sorry to hijack the thread a bit but i've wondered some of these same questions as i'm interested in supercharging too and know I'll need bigger rubber to do so. . .so assuming i DONT lower the car, is the wider wheel going to rub if I go past 305? or is it just a matter of cosmetics with the wheel sticking out past the fender? can you add fender flares and not lower it and run larger than a 305?
Drifting
Joined: Oct 2013
Posts: 1,746
Likes: 1,300
From: Fort McMurray Alberta
2018 C7 of Year Finalist
God I hate this debate. I'm looking at getting 325's in the rear on 12" wheels and I have lots of people telling me they won't rub and will be fine, and I have some people saying 315's rub. I don't understand how this can be so uncertain.
Melting Slicks
Joined: Sep 1999
Posts: 2,305
Likes: 87
From: Richmond, BC, Canada
Different people, different information.
Here's my info...
First, I have custom wheels.
19x10 front with 56mm offset
20x11 rear with 79 mm offset
Note my offsets are the same as Z51 OEM.
I think this is a major consideration in rubbing or not.
Toyo R888 tires
295x30x19 front
315x30x20 rear
I did lower the car on the stock bolts (about 1/2 inch), but I DID get rub.
This was NOT from cornering, but while driving on the road... undulations in road surface.
So I raised it back to stock height (about 1/2 inch).
I also have some pretty extreme camber
-2.5 front
-2.0 rear
To get this I removed all the washers (2 on each bolt) from all the A-arms.
I also have an LG Motorsports G7 sway bar kit.
Note I have re-installed the OEM Z51 rear bar, to address oversteer.
I still have some oversteer, so I am looking at other options to fix this.
We Autocross extensively; no drag racing.
In any event..... NO RUBBING !!!!!!!!!!
Here's my info...
First, I have custom wheels.
19x10 front with 56mm offset
20x11 rear with 79 mm offset
Note my offsets are the same as Z51 OEM.
I think this is a major consideration in rubbing or not.
Toyo R888 tires
295x30x19 front
315x30x20 rear
I did lower the car on the stock bolts (about 1/2 inch), but I DID get rub.
This was NOT from cornering, but while driving on the road... undulations in road surface.
So I raised it back to stock height (about 1/2 inch).
I also have some pretty extreme camber
-2.5 front
-2.0 rear
To get this I removed all the washers (2 on each bolt) from all the A-arms.
I also have an LG Motorsports G7 sway bar kit.
Note I have re-installed the OEM Z51 rear bar, to address oversteer.
I still have some oversteer, so I am looking at other options to fix this.
We Autocross extensively; no drag racing.
In any event..... NO RUBBING !!!!!!!!!!
Last edited by NTMD8R; Nov 5, 2015 at 11:30 AM.
Instructor
Joined: Nov 2014
Posts: 129
Likes: 50
At the drag strip i went from a 2.00 60ft with stock runflats to a 1.81 60ft with 295 r888. I will tell you i did spin all other runs and i wasnt supercharged. Unless the track prep is excellent you will have a hard time hooking at your power level with r888's. The r888's are made for road racing , not drag racing and have a very stiff sidewall..I recomend getting the nittos nt05r or the mickey thompson et streets ll..
Drifting
Joined: Oct 2013
Posts: 1,746
Likes: 1,300
From: Fort McMurray Alberta
2018 C7 of Year Finalist
315 will be too wide.
At the drag strip i went from a 2.00 60ft with stock runflats to a 1.81 60ft with 295 r888. I will tell you i did spin all other runs and i wasnt supercharged. Unless the track prep is excellent you will have a hard time hooking at your power level with r888's. The r888's are made for road racing , not drag racing and have a very stiff sidewall..I recomend getting the nittos nt05r or the mickey thompson et streets ll..
At the drag strip i went from a 2.00 60ft with stock runflats to a 1.81 60ft with 295 r888. I will tell you i did spin all other runs and i wasnt supercharged. Unless the track prep is excellent you will have a hard time hooking at your power level with r888's. The r888's are made for road racing , not drag racing and have a very stiff sidewall..I recomend getting the nittos nt05r or the mickey thompson et streets ll..
Burning Brakes
Joined: Sep 2011
Posts: 960
Likes: 40
Outside rear fender fitment is easy:
285 tire at 65mm wheel offset
295 tire at 70mm wheel offset
305 tire at 75mm wheel offset
315 tire at 79mm wheel offset
325 tire at 85mm wheel offset (Inside clearance is unknown and likely needs work. Minimum 19" diameter wheel.)
Each tire is on its spec wheel width.
This is not allowing for different camber settings.
This is not allowing for setups that stick out the tires.
People that say that something will not fit often don't know their wheel offset. Or they are lowered on lowering bolts. Or they are using large diameter tires.
If the car is lowered it also needs a stiffer suspension
.
285 tire at 65mm wheel offset
295 tire at 70mm wheel offset
305 tire at 75mm wheel offset
315 tire at 79mm wheel offset
325 tire at 85mm wheel offset (Inside clearance is unknown and likely needs work. Minimum 19" diameter wheel.)
Each tire is on its spec wheel width.
This is not allowing for different camber settings.
This is not allowing for setups that stick out the tires.
People that say that something will not fit often don't know their wheel offset. Or they are lowered on lowering bolts. Or they are using large diameter tires.
If the car is lowered it also needs a stiffer suspension
.
Last edited by B Stead; Nov 5, 2015 at 03:13 PM.
Team Owner
Joined: Jan 2007
Posts: 29,063
Likes: 1,839
From: cookeville tennessee
Toyo R888 has a little more stiffer side wall than the MT does but the R888 hooks really good so good than a few guys have broken axels from the rwhp that has a blower on the car...Robert
Drifting
Joined: Oct 2013
Posts: 1,746
Likes: 1,300
From: Fort McMurray Alberta
2018 C7 of Year Finalist
Outside rear fender fitment is easy:
285 tire at 65mm wheel offset
295 tire at 70mm wheel offset
305 tire at 75mm wheel offset
315 tire at 79mm wheel offset
325 tire at 85mm wheel offset (Inside clearance is unknown and likely needs work. Minimum 19" diameter wheel.)
Each tire is on its spec wheel width.
This is not allowing for different camber settings.
This is not allowing for setups that stick out the tires.
People that say that something will not fit often don't know their wheel offset. Or they are lowered on lowering bolts. Or they are using large diameter tires.
If the car is lowered it also needs a stiffer suspension
.
285 tire at 65mm wheel offset
295 tire at 70mm wheel offset
305 tire at 75mm wheel offset
315 tire at 79mm wheel offset
325 tire at 85mm wheel offset (Inside clearance is unknown and likely needs work. Minimum 19" diameter wheel.)
Each tire is on its spec wheel width.
This is not allowing for different camber settings.
This is not allowing for setups that stick out the tires.
People that say that something will not fit often don't know their wheel offset. Or they are lowered on lowering bolts. Or they are using large diameter tires.
If the car is lowered it also needs a stiffer suspension
.
Also, on the stiffer suspension for lowered cars, would running in track mode all the time solve this problem?
Last edited by blue_bomber697; Nov 5, 2015 at 05:01 PM.
Thread Starter
Cruising
Joined: Nov 2015
Posts: 12
Likes: 0
Haha. I hear you! NTMD8R probably said it best. It depends on the rim size, if its lowered, camber, etc. Even so with all the searching I've been doing I still feel like people claim different results.NTMD8R.. do your toyo 888's stick well for launches? or maybe should i say good enough for a car with such high tq? I've been going back and forth between the Toyo 888's or the nt555r tires for just my two rear tires. This is still my daily driver so I wanted to also be able to drive it cautiously in the rain and have some fun at the drag strip. I'd rather have a safer street tire than a better drag tire.
Last edited by 9psi; Nov 5, 2015 at 05:37 PM.
Thread Starter
Cruising
Joined: Nov 2015
Posts: 12
Likes: 0
Melting Slicks
Joined: Sep 1999
Posts: 2,305
Likes: 87
From: Richmond, BC, Canada
When I compete in an Autocross run, I have all the nannies off;
the whole object is to get going !!!!!
So tire spin is not desirable.
So I rev it up a bit (2000) to launch, and then let's go.
Any more, and they will spin.
the whole object is to get going !!!!!
So tire spin is not desirable.
So I rev it up a bit (2000) to launch, and then let's go.
Any more, and they will spin.
Last edited by NTMD8R; Nov 5, 2015 at 06:57 PM.