To 315 or not 315

[project hotrod]

I've been crunching numbers between tire combinations for the Malibu and I fail to see a large advantage going through the work to fit a 315 in the wheel well.

Against a 275 tire I would only gain 1.7" more tread width and would need to run a heaver 11" wheel opposed to getting away with a 9.5"

Sidewall thickness and overall diameter are within .01 between both too.

Not mentioning all the work and cost in the mini tubs and sectioning the rail for a car that will only make around 400 wheel hp.

I guess if I was more after looks a 315 would look tougher but this project is more about function.

The combination which I think will offer the best fitment, and performance would be.

rear
275-40-17 (9.5" wheel) dia 25.6" - tread 9.8" - sidewall 4.3"
front
245-45-17 (8.0" wheel) dia 25.8" - tread 8.3" - sidewall 4.4"

I know I have a greater overall on the front by .2" but I think going to a 245-40-17 with a overall dia of 24.72 would be too small.

Would anyone care to share an opinion on this or validate my theory considering my experience is drag racing?

I would greatly appreciate since I'm close to pulling the trigger on tires and wheels.

[68Formula]

A 315, looks killer no doubt.

As far as traction, the more tire on the road the better. However, I've heard people say that you want your front/rear sizes within 40mm or so to balance handling (of course that varies car to car due to the thousands of other factors affect handling balance).

Also, as you said, mini-tubbing is a slippery slope. Things that need to be considered i addition to the tubs themselves (depending on vehicle model):

Narrowing the gas tank
Notching (or removing completely) the rear seat for clearance
Rearend suspension changes (for leafspring, offsetting the mounting, think most of the aftermarket 3 & 4 link setups are designed with tubbing in mind)
Narrowing the rearend (you could adjust by using wheel offsets, but to me the deep dish look is part o f the bad @$$ you get with mini-tubbing)
Exhaust modification


I couldn't justify the cost in all this for myself, so I jammed in what fit.

BTW, you meant 245/45R17 for the front, right?

[project hotrod]

Thanks for the reply. :)

My initial tires chosen are ZR rated but yeah. 245/45/17 on the front is what I'm thinking.

To me, if the work and money = a large increase in ability I have no problem putting a 315 under it. ie: seconds off of lap times rather than tenths since I won't be competing on a serious level.

I'll be using a 3-link with a watts so I don't have to worry about exhaust, backseat, and so on... I'll also be using a fuel cell so the clearance issues are moot... The problem is I haven't found any imperical data supporting just how much better the 315 would handle over the 275 or even a 285 for that matter.

Regarding your 40mm rule of thumb: With a 275 / 245 combination I have a difference of 38.10mm which should be fine. :)

It's kind of funny but the decision on tires decides quite a bit of the build, and purchase order of parts depending on the choice.

[Damn True]

You can always put on a smaller tire once the car is finished if you find it difficult to attain balance. Putting on larger tires after the fact would be far more difficult.

[project hotrod]

You can always put on a smaller tire once the car is finished if you find it difficult to attain balance. Putting on larger tires after the fact would be far more difficult.

I'll just cut the wheel wells ala Street stock roundy round cars. lol

[86Cutlass383SR]

Kevin I'm in basically the planning stages for my 86 Cutlass and I've mentally battled that same question. 315 would look cool...but between the frame notch and mini-tubs plus whatever else I run into, the 315's just aren't worth it to my build.

Another factor in my decision is the fact that I plan on making some lengthy road-trips *if* I ever get mine road worthy. The question in my mind is, if I cut a tire and need a replacement, what's the chance of finding a tire dealer with a 315 vs a 275? I'd think a 275 would be slightly less difficult to find. I may be wrong.

[Samckitt]

I have 275's out back with 245's up front. I too want to put 315's out back mainly for looks but seems a lot of work just for the look.

[68Formula]

The question in my mind is, if I cut a tire and need a replacement, what's the chance of finding a tire dealer with a 315 vs a 275? I'd think a 275 would be slightly less difficult to find. I may be wrong.

The 275/45R17s were used on factory Camaros, Firebirds, and other makes. It's a common OEM performance size tire, so replacements are readily available.

[JRouche]

I ended up with a 275 mainly due to wheel selection. I wanted 315mm tires but no 11" wheels in a soft lip hoop. Custom sure, add 400 a wheel. So I went with 10" billet specialties and GY F-1's in 275. They look ok. (62 Nova) ALOT of tire choices in 275.. JR
https://static1.pt-content.com/images/pt/2009/01/wheels2-1.jpg

[dlrepmn]

315's just for looks, yes. That's true. But you have to admit they look pretty good.

https://static1.pt-content.com/images/noimg.gif

Is it worth the grief and expense? You have to decide. To get a decent size tire on an F-body you have to mini-tub. You are at pretty good size without it. Don't forget you have to modify your rear seat frame as well with the mini-tub.

Looking at JR's you have a tough time telling between a 315 on a 12" rim and a 275 on an 10" rim. I'm sure if you looked from directly behind the car you could, but would you find a tremendous difference in performance unless you were on a track?

I have a 400HP motor, but I didn't have a choice if I wanted decent sized meats. You do.

[JRouche]

Looking at JR's you have a tough time telling between a 315 on a 12" rim and a 275 on an 10" rim. I'm sure if you looked from directly behind the car you could, but would you find a tremendous difference in performance unless you were on a track?

Ummm, I screwed up. They are 285 tires :) Not much diif though from the 275. Im an idiot LOL Dont even know what tire Im using LOL Oh, the GY F-1s tend to run a lil wider than some. JR

[SicMonte]

I had a 315 out back and I only had a frame notch done. The rims were 17x11 with 5.5 bs but a 6.0bs would have been better.

Have you ever thought about going for a 305?

[syborg tt]

I'm sorry i disagree - they look great.



I ended up with a 275 mainly due to wheel selection. I wanted 315mm tires but no 11" wheels in a soft lip hoop. Custom sure, add 400 a wheel. So I went with 10" billet specialties and GY F-1's in 275. They look ok. (62 Nova) ALOT of tire choices in 275.. JR
https://static1.pt-content.com/images/pt/2009/01/wheels2-1.jpg

[SS1156]

The problem with 315's is there aren't many tires to choose from. I have a 96 Camaro SS and the factory tire is a 275/40ZR17. I was gonna put 11's on the back with 315's but there weren't enough tire choices so I left the car stock. Now that I have a 72 and I'm gonna mini tub it I have all the choices in the world. Good luck with the tire pickins. BTW, the GS -D3's look awesome on there and they are an awesome tire too. They do run large for there size.

[andrewb70]

I'd go with a 285/40-17 in the rear and 245/45-17 in the front. The 285s are just slightly taller which I think will look better.

http://www.tirerack.com/tires/Spec.jsp?make=Goodyear&model=Eagle+F1+GS-D3&partnum=84YR7F1GSD3&vehicleSearch=false&fromCompare1=yes&place=1

Andrew

[BigBlockOlds]

I had a 315 out back and I only had a frame notch done. The rims were 17x11 with 5.5 bs but a 6.0bs would have been better.

Same here. Although I have a 6" BS and I did move my stock wheel wells in just a touch (maybe 1" or so). But the rear seats and trunk hinges still fit.

[DAK]

I'd go with a 285/40-17 in the rear and 245/45-17 in the front. The 285s are just slightly taller which I think will look better.

285's on the left. I had 275's on the back of my car for a fews yrs and a taller tire would fill the wheel well nicer. I didn't realize how much bigger the 285's were over 275's but I hope they fit.:)

https://static1.pt-content.com/images/pt/2009/02/0073-1.jpg

[JRouche]

285's on the left. I had 275's on the back of my car for a fews yrs and a taller tire would fill the wheel well nicer. I didn't realize how much bigger the 285's were over 275's but I hope they fit.:)

Wow!!! Thats really odd. Are those 275s on the right. There should only be a total of LESS than one inch (more like .800") for the whole stack. Im I losing my mind, yeah, yeah, I did find it again, but I swear its on the way out again. Tell me they are not 275s on the right? JR

[Throttle]

315's just for looks, yes. That's true. But you have to admit they look pretty good.

https://static1.pt-content.com/images/noimg.gif

Is it worth the grief and expense? You have to decide. To get a decent size tire on an F-body you have to mini-tub. You are at pretty good size without it. Don't forget you have to modify your rear seat frame as well with the mini-tub.

Looking at JR's you have a tough time telling between a 315 on a 12" rim and a 275 on an 10" rim. I'm sure if you looked from directly behind the car you could, but would you find a tremendous difference in performance unless you were on a track?

I have a 400HP motor, but I didn't have a choice if I wanted decent sized meats. You do.

You can run a 315 under a real F-Body..:enguard::rolleyes:

https://static1.pt-content.com/images/pt/2009/02/2762748305_a5f3da4334_b-1.jpg

[syborg tt]

Wow!!! Thats really odd. Are those 275s on the right. There should only be a total of LESS than one inch (more like .800") for the whole stack. Im I losing my mind, yeah, yeah, I did find it again, but I swear its on the way out again. Tell me they are not 275s on the right? JR

could also be 8" rim vs 10" rim

[JRouche]

could also be 8" rim vs 10" rim

Good point. But from the looks of it the new tires are unmounted, still strapped up. I wonder if those are the front tires on the right. Cause the diff between a 285 and a 275 is only .400" Those look to be off by three or more inches total (both tires).

And the white car, with the 315s. Look small to me. Are they Sumitomos??? There is a pic around with a stack of 315 sumis next to some goodyears and there is a couple inches diff. JR

Oh, here it is. Both 315s. A lil diff in sizes
http://209.85.173.132/search?q=cache:DI_mYfckkJcJ:forums.corral.net/forums/showthread.php%3Ft%3D1051408+sumitomo+goodyear+315&hl=en&ct=clnk&cd=1&gl=us
https://static1.pt-content.com/images/pt/2009/02/100_0053-1.jpg

[Throttle]

Yeah, they are Sumi's, I have some M/T Street Radials for it, I just use these tires to roll it around.. :D

[DAK]

Wow!!! Thats really odd. Are those 275s on the right. There should only be a total of LESS than one inch (more like .800") for the whole stack. Im I losing my mind, yeah, yeah, I did find it again, but I swear its on the way out again. Tell me they are not 275s on the right? JR


275's on a 9.5in rim on the right. It maybe just a dilusion now but I'll see how they compare when the 275's show cords and then I need to mount the 285's. :)

[DLinson]

I have 245-40/R17 front and 315-35/r17 rear on my 62 Nova. I think the 40 series front looks good. I used a 10 inch rear rim with Summitomo tires. They fit on the rim fine, Sumitomo is the only tire manufacture that shows 10 inch rims as an acceptable rim width for 315's. If the pic above is real, I guess we know why. The sidewalls are not nearly as stiff as other tires. They were pretty easy to install on the reverse drop center rims. The Sumitomo's are only $99 pre rear tire on the Tire Rack. Just hard to turn down that price. They grip pretty good, not as good as the Nittos or BFG's but I'm not out to win races either. You also don't mind doing smoky burnouts when they are that cheap.

[JRouche]

I have 245-40/R17 front and 315-35/r17 rear on my 62 Nova. I think the 40 series front looks good. I used a 10 inch rear rim with Summitomo tires. They fit on the rim fine, Sumitomo is the only tire manufacture that shows 10 inch rims as an acceptable rim width for 315's. If the pic above is real, I guess we know why. The sidewalls are not nearly as stiff as other tires. They were pretty easy to install on the reverse drop center rims. The Sumitomo's are only $99 pre rear tire on the Tire Rack. Just hard to turn down that price. They grip pretty good, not as good as the Nittos or BFG's but I'm not out to win races either. You also don't mind doing smoky burnouts when they are that cheap.

Nice looking car... Yeah, I saw those 99 dollar sumis. Almost wanna buy a few sets for the future at that price. JR

[Throttle]

Yeah, I have the Sumi's because they where cheap and they are my roll around tires and I will probably use them for the break in period for the motor and then roast them off and put the Mickeys on.. :D

[JRouche]

Yeah, I have the Sumi's because they where cheap and they are my roll around tires and I will probably use them for the break in period for the motor and then roast them off and put the Mickeys on.. :D

Must be nice. Shoulda seen my roll around tires and rims. Four different rims with four different BALD tires to boot. Junk yard special for they day, he said all four for 50 bucks. Made me happy cause at the time all I had was axles with no wheels.

Oh, and now Im trying to stuff one each week into the trash can that they pick up every week. They frown on the tires and rims. Geeze, they dont want a landfill full of tires :) JR

[Throttle]

I had these on my car as my roll around wheels and tires, but I ended up putting them on a customer's car so that we could push it around.. It has been 3 months and we still havent recieved the new wheels for the customer's car and I am stuck with my Boyds on my car.. :(
https://static1.pt-content.com/images/pt/2009/03/2604319798_2df3acd0fc_b-1.jpg

[gnxtreme]

I have an 84 Regal with a frame notch. I run those "crappy SUMITOMO 315's on 11" black ZR1 wheels. Sorry no pics yet but Ill try this week. A lot of guys may not like this but .....If you dont have 315s at a minimum you have SKINNY RUBBER. Leave the little
tires for the civics. Notch the frame, and bash the wheelwells no other work needed. I did mine in about 12 hours. START CHOPPING!!:yum:

[JRouche]

I have an 84 Regal with a frame notch. I run those "crappy SUMITOMO 315's on 11" black ZR1 wheels. Sorry no pics yet but Ill try this week. A lot of guys may not like this but .....If you dont have 315s at a minimum you have SKINNY RUBBER.

LOL And you may not like this but YOU have skinny tires :) The sumi 315s are 285s. JR

[BigBlockOlds]

I've heard that as well. Luckily the frame notch on my car will accomodate a 335 series tire so a "true" 315 shouldn't be a problem.

[1badchevelle]

can a 20 x 10 rim fit a 305 or a 315 tire?

[BigBlockOlds]

I decided to measure my Sumitomo's today while cleaning the barn.

According to www.tirerack.com, the Sumitomo 315 tire should have a 12.6" section width if mounted on an 11" rims. My rims are 11" wide and I came up with 12.25" in section width. So their specs are off from what they say they should be. Actually, the 12.25" is closer to what the Goodyear's are supposed to be.
That picture above looks more like a comparison between a set of 315's and 335's or 345's.

[79cutlass]

I agree with BigBlock on the Sumi's I have them on 11" as well and measured the same as he did. The more rounded edges and no rim guard make them look skinnier but who cares for a $100 315 you cant beat em!

[ponchopwr70]

Heres some pics of a 315 nitto dr on a 9.5 rim. They weren't very much bigger than the 285's I took off.


https://static1.pt-content.com/images/noimg.gif (http://s110.photobucket.com/albums/n92/ponchopwr70/?action=view&current=Picture005.jpg)
https://static1.pt-content.com/images/noimg.gif (http://s110.photobucket.com/albums/n92/ponchopwr70/?action=view&current=Picture004.jpg)
https://static1.pt-content.com/images/noimg.gif (http://s110.photobucket.com/albums/n92/ponchopwr70/?action=view&current=Picture007.jpg)
https://static1.pt-content.com/images/noimg.gif (http://s110.photobucket.com/albums/n92/ponchopwr70/?action=view&current=Picture003.jpg)
https://static1.pt-content.com/images/noimg.gif (http://s110.photobucket.com/albums/n92/ponchopwr70/?action=view&current=Picture001.jpg)

[JRouche]

I decided to measure my Sumitomo's today while cleaning the barn.

According to www.tirerack.com (http://www.tirerack.com), the Sumitomo 315 tire should have a 12.6" section width if mounted on an 11" rims. My rims are 11" wide and I came up with 12.25" in section width. So their specs are off from what they say they should be. Actually, the 12.25" is closer to what the Goodyear's are supposed to be.
That picture above looks more like a comparison between a set of 315's and 335's or 345's.

Tire racks numbers are off. And GY F1s do run large, like BFGs. I have GY F1s in 285mm and tire rack shows a section width of 11.3" on a 10" rim. I have them mounted on 10" wheels and just measured, they are 12" even, a 1/4" shy of sumi 315s. Sumis do run small but for a 100 dollar tire, that gets great reviews for performance you cant beat it. JR

[gnxtreme]

Heres a Pic of my 17 x11 Grand sport rims with Summitomo 315 35 17s on the back. The fronts are 255 40 17s on 17 x 9.5s
YUM.

[MickMc]

Is this a real question?

larger tires or smaller tires?

If you want all of the justifications of ease or being practical or cost, don't ask us.
For a practical answer answer ask you wife or just buy new car/suv/prius.

This is not about being practical, this is Hot Rodding, how far can you go, how far can you afford (time, money, energy) to go?

The cars you dream about never asked 'where will I find a replacement tire' if I have a problem in the middle of nowhere.
The cars you dream about never asked 'which is the most affordable way to go'.

pick your path wisely...your limitations are the only ones to consider, not someone else's limitations.

Cost benefit analysis does not equal Hot Rodding.

Follow your own path, we will all respect you for what you have done and your decisions.

You not be judged by the size of your tires, only how you used them.


Mick

[86Cutlass383SR]

The cars you dream about never asked 'where will I find a replacement tire' if I have a problem in the middle of nowhere.

Mick

I ask myself this question as my car isn't parked comfortably on a platform cruising behind my Silverado. It's acutally on the pavement tires going round and round. Thus, with everything on the roads today, and you put enough miles on your car, then eventually you will have that experience.

Yeah, I ask myself questions such as this. I'm not blessed to have such nice tracks in my back yard. If I take my car somewhere it usually involves from 100 - 300 mile trip one-way.

Believe me, in my mind, that 335 or 315 isn't gonna look as kewl flat on the back of my car if I can't get a replacement tire out in the middle of BFE.

If I only had to drive 50 mile and a phone call could get me a replacement tire in an hour, then go for it.

My intentions aren't meant as a flame, just an explaination of my way of thinking. Call it practicality over extreme if you want. I like driving my car and having "replacable" parts on it if needed miles away from home.

[madcarson]

I'm running 335/35/16 on my 69 with no mods other than springs to keep off wheel well lip,I do want to mini tub etc in future so they will be tucked inside!

[MickMc]

I ask myself this question as my car isn't parked comfortably on a platform cruising behind my Silverado. It's acutally on the pavement tires going round and round. Thus, with everything on the roads today, and you put enough miles on your car, then eventually you will have that experience.

Yeah, I ask myself questions such as this. I'm not blessed to have such nice tracks in my back yard. If I take my car somewhere it usually involves from 100 - 300 mile trip one-way.

Believe me, in my mind, that 335 or 315 isn't gonna look as kewl flat on the back of my car if I can't get a replacement tire out in the middle of BFE.

If I only had to drive 50 mile and a phone call could get me a replacement tire in an hour, then go for it.

My intentions aren't meant as a flame, just an explaination of my way of thinking. Call it practicality over extreme if you want. I like driving my car and having "replacable" parts on it if needed miles away from home.


I totally understand the replacement thing. And I agree.

I live in New Mexico and even the replacement Potenza's for my Impala are hard to find.
And we have to drive at least 400 miles for a cool event too.

Let me use an extreme example.
I have 39 Boggers on my truck, and that truck has been everywhere, and I know there is no way I'm going to find a replacement for that tire on some trip to the middle of nowhere, but I still have Boggers and I still drive the truck.
Yes, a spare that will get me down the road is helpful, a spare 39 TSL Bogger is huge, so a very narrow just as tall spare is needed.
Fix-a-flat, onboard air, bead breakers, all much eaiser to carry in an 8ft bed, than the trunk of car.

Yes, the more time you spend on the road the more likely you are to have a problem, but don't let that deter you.

I remember when Scott Sullivan and Jeff Smith drove across country in Scott's 55, (Cheese Whiz) huge Mickey's out back and Motor Fly wheels. I thought he was crazy, what if he has a problem.
He did have a couple of problems, and a few friends and some tools in the trunk and a phone call or two.
Eventfull yes, overcome-able yes.
And I will claim thats what started the Power Tour.
Jeff will never cliam that though.


OK extreme is MUCH more difficult to pull-off.
A prius is very easy to pull-off.

You will find the perfect balance between the two, and most likely you will step back and say I could have gone just a little bit further.

My buddy makes the same trips as I do on 44 boggers, dam I hate him.
But I break fewer Dana 60 axles, na na.
Nobody has replacement axles in stock...
I once drove home in front wheel drive for 370 miles after fishing out out the broken axles parts. Extra capacity diff covers, gear oil eveywhere that needed to be reused, how to remove a broken axle in the outback and miles from home. Front wheel drive and 40 inch Hawgs (at the time), that will keep your hands glued to the steering wheel at 50 miles an hour.

How about a 4 L60E with two gears, no overdrive and 470 miles from home. Do you drive it and risk it exploding or cross your fingers and head home...


Mick

PS. new GTO's have a very small spare that clears big brakes, try evil bay...

[zman1969]

285's on the left. I had 275's on the back of my car for a fews yrs and a taller tire would fill the wheel well nicer. I didn't realize how much bigger the 285's were over 275's but I hope they fit.:)

https://static1.pt-content.com/images/pt/2009/02/0073-1.jpg
that really doesn't look right there should be only 1 cm difference in width that's how they're sized but by mm - seems silly mfrs cant measure their own tires right! a 275 should be a 275 by no matter what the brand but they are not.