Question about low vs. high profile tires on the track

[decimation1]

Pretty simple question---- for the track would I be better off with my stock wheels and tires or my 19s with lower profile tires?

Thanks,

Chris

[MSteve5036]

Originally Posted by decimation1

Pretty simple question---- for the track would I be better off with my stock wheels and tires or my 19s with lower profile tires?

Thanks,

Chris

Depends on a lot of factors like track and tire...I will say this though...if they are both street tires....just chew up the cheaper ones (assuming stock)

[jphughan]

All else being equal, larger diameter tires give you an increase in longitudinal contact patch size, which helps with acceleration and braking (though changes in unsprung weight between two proposed setups will also affect this), and a thinner sidewall will flex less. From a practical standpoint, a 35 vs 40 aspect change isn't a major difference (40 is hardly high profile), 18s are cheaper to run, and unless you're already very fast on track, more dollars spent on track days will have a bigger impact on making you faster and give you more fun than more dollars spent on a "better" tire setup. But as was said above, if you plan to do more than about 4 track days per year, step up from PSS to something like AD08R. Their stiffer sidewalls mean they'll last much LONGER than PSS on a dual purpose car despite the lower treadwear rating because they won't prematurely cord or chunk on the outsides. I got 5 track days out of PSS before that happened, and I got 12 track days out of my AD08Rs before the tread meant replacement time. I do NOT recommend that a novice or even intermediate driver go to something like NT01, Cup 2, or even RE-71R since that seems to be similar to Cup 2 even though it's classified as Extreme Summer, and many DE organizers won't allow less experienced drivers to run such tires anyway.

[roastbeef]

what are you running stock? the oem 18's?
the 18's will be better for track use. i actually like a little more rubber for the track, its less harsh on everything (wheels, suspension, etc..) when you bounce off a rumble strip or go off.

[macdude357]

Originally Posted by roastbeef

what are you running stock? the oem 18's?
the 18's will be better for track use. i actually like a little more rubber for the track, its less harsh on everything (wheels, suspension, etc..) when you bounce off a rumble strip or go off.

I thought that most track guys run 35's even with their 18" tires (275/35/18) so there would be no difference in sidewall height between those and the 19" 35's, right?

[jphughan]

Originally Posted by macdude357

I thought that most track guys run 35's even with their 18" tires (275/35/18) so there would be no difference in sidewall height between those and the 19" 35's, right?

Yes they run 35s, but that's because with a 275 width, a 40 would become too tall since the aspect figure determines sidewall height as a percentage of tire width. A 275/40/18 is almost half an inch taller than the stock front 245/40, whereas a 275/35 is only 1/16" shorter. 275/40/18 may also not have desired tire selections.

[roastbeef]

yea, the sidewall number represents different depths since it is relative to a percentage of the tire width. just eyeballing it, i can tell you my 275/35/18's had a thicker sidewall than my 275/35/19's.

[jphughan]

Originally Posted by roastbeef

yea, the sidewall number represents different depths since it is relative to a percentage of the tire width. just eyeballing it, i can tell you my 275/35/18's had a thicker sidewall than my 275/35/19's.

That shouldn't be the case since aspect doesn't take tire diameter into account. But it can happen if the tires are different types (Yokos run wide and therefore might have a higher sidewall for the same width rating, and some sidewalls are just more vertical) or depending on the width of the wheel (wider wheels make for shorter sidewalls) or just the visual illusion of a given sidewall thickness appearing greater when the inside diameter is smaller.

[roastbeef]

could be, i'm certainly no expert. maybe its an optical illusion on my smaller wheels...

[decimation1]

Originally Posted by roastbeef

what are you running stock? the oem 18's?
the 18's will be better for track use. i actually like a little more rubber for the track, its less harsh on everything (wheels, suspension, etc..) when you bounce off a rumble strip or go off.

I have OEM 18s and I have DINAN 19s 275/30 front and 295/30 rear. I was kind of thinking the same thing about running the OEMs, but the tire size of the DINAN wheels make it stick like a monster.

[jphughan]

Originally Posted by decimation1

I have OEM 18s and I have DINAN 19s 275/30 front and 295/30 rear. I was kind of thinking the same thing about running the OEMs, but the tire size of the DINAN wheels make it stick like a monster.

There's something to be said for not having as much grip as a novice. It allows you to learn to work with what you have rather than counting on insane grip to cover up/fix mistakes, and lower overall speeds are safer anyway. The same idea applies with horsepower -- students will learn more and improve more rapidly in a slow car than a fast car. And if you run the 19s on the road, dedicate the OEMs to track duty at least for now maybe with something like AD08Rs if this becomes a habit. Smaller wheels and tires can also make the car feel more nimble due to reduced unsprung weight, which means they actually improve performance in all cases that aren't traction-limited.

[decimation1]

Originally Posted by jphughan

There's something to be said for not having as much grip as a novice. It allows you to learn to work with what you have rather than counting on insane grip to cover up/fix mistakes, and lower overall speeds are safer anyway. The same idea applies with horsepower -- students will learn more and improve more rapidly in a slow car than a fast car. And if you run the 19s on the road, dedicate the OEMs to track duty at least for now maybe with something like AD08Rs if this becomes a habit. Smaller wheels and tires can also make the car feel more nimble due to reduced unsprung weight, which means they actually improve performance in all cases that aren't traction-limited.

Thanks, that the exact input I was looking for. The DINAN 19s are great but they are harsh on rough roads, even in comfort mode. I had 2 track days scheduled, 1 in June and 1 in July at Dominion Raceway and the both got cancelled. Looking for another now close to central Va. Any thoughts would be appreciated.

[bigjae1976]

Tire sidewall plays a role in the effective spring rate of the suspension. And all of this other stuff.

But let me make it easy for you...

Smaller diameter wheels = cheaper tires = more time on track.

/thread

[dparm]

Originally Posted by jphughan

I do NOT recommend that a novice or even intermediate driver go to something like NT01, Cup 2, or even RE-71R since that seems to be similar to Cup 2 even though it's classified as Extreme Summer, and many DE organizers won't allow less experienced drivers to run such tires anyway.

I have never come across a group that didn't allow somebody to run a specific tire. Depending on the club, an R-compound tire might automatically move you into an "anything goes" group where you'll be up against trailered-in race cars. Then again, I don't run with groups like SCCA or NASA.

I do agree that ultra-grippy tires like the ones you mentioned are a bad idea for beginners as they really tend to hide mistakes and allow you to develop bad habits.

I run AD08R and agree that it's about as aggressive as I'd ever go for dual-purpose; the ride quality on the street is a lot harsher than the PSS, but even after 6 track days they look great whereas the PSS looked like shit after 1 or 2.

[jphughan]

Originally Posted by dparm

I have never come across a group that didn't allow somebody to run a specific tire. Depending on the club, an R-compound tire might automatically move you into an "anything goes" group where you'll be up against trailered-in race cars. Then again, I don't run with groups like SCCA or NASA.

I do agree that ultra-grippy tires like the ones you mentioned are a bad idea for beginners as they really tend to hide mistakes and allow you to develop bad habits.

I run AD08R and agree that it's about as aggressive as I'd ever go for dual-purpose; the ride quality on the street is a lot harsher than the PSS, but even after 6 track days they look great whereas the PSS looked like shit after 1 or 2.

Take a look at this tire policy from a popular DE organizer in TX: http://thedriversedge.net/tires.htm. Seems that as long as they're DOT-approved and 120+ TW, they're ok for anyone, which would allow tires like MPSC2, but not NT-01. I remember the rules being more strict than that, but I could be wrong or they might have changed their rules.

I don't remember a dramatic difference between PSS and AD08R in terms of road ride. I was running a stock non-ZCP EDC suspension except for camber plates. The only place I noted a difference was over things like freeway expansion joints and other road irregularities, although I suppose the local road quality would influence ride impressions quite a bit. Wrote a long comparison here: http://www.m3post.com/forums/showthread.php?t=1044773.

[dparm]

Originally Posted by jphughan

I don't remember a dramatic difference between PSS and AD08R in terms of road ride. I was running a stock non-ZCP EDC suspension except for camber plates. The only place I noted a difference was over things like freeway expansion joints and other road irregularities, although I suppose the local road quality would influence ride impressions quite a bit. Wrote a long comparison here: http://www.m3post.com/forums/showthread.php?t=1044773.

It was precisely those things: expansion joints and large seems/irregularities. The ride quality has definitely gone down and can be very jarring. If I had to do it again, I don't know if I would've bought the AD08R, to be completely serious.

[jphughan]

Originally Posted by dparm

It was precisely those things: expansion joints and large seems/irregularities. The ride quality has definitely gone down and can be very jarring. If I had to do it again, I don't know if I would've bought the AD08R, to be completely serious.

Fair enough. I guess the roads around here just don't have very many of those problem areas.

[The HACK]

In theory, the golden sweet spot on tire size is:

Run the SMALLEST wheel diameter that will clear the brakes, and NARROWEST tire that won't overheat given your car's power and weight (and your particular driving style) with the aspect ratio that comes closes to matching the overall OEM tire diameter.

So if 17" rims fit over the brakes without interference and/or need of spacers, and 265mm wide tires don't get past the sweet spot in tire temp on your brand of tire choice? No reason to run any bigger since 1) 17" track tires are cheaper and 2) 17" and 265mm wide track tires are lighter than 18" and 275mm.

Then again, if you're given 295/30/19s to run for FREE? Run the damn 295/30/19s. If they fit. If they don't fit, go wide body kit and make them fit.

[Richbot]

I prefer 275/65-18's, much faster than 275/35-18's for truck use and hold up better session after session at truck days

[z3papa]

Originally Posted by jphughan

All else being equal, larger diameter tires give you an increase in longitudinal contact patch size, which helps with acceleration and braking (though changes in unsprung weight between two proposed setups will also affect this), and a thinner sidewall will flex less. From a practical standpoint, a 35 vs 40 aspect change isn't a major difference (40 is hardly high profile), 18s are cheaper to run, and unless you're already very fast on track, more dollars spent on track days will have a bigger impact on making you faster and give you more fun than more dollars spent on a "better" tire setup. But as was said above, if you plan to do more than about 4 track days per year, step up from PSS to something like AD08R. Their stiffer sidewalls mean they'll last much LONGER than PSS on a dual purpose car despite the lower treadwear rating because they won't prematurely cord or chunk on the outsides. I got 5 track days out of PSS before that happened, and I got 12 track days out of my AD08Rs before the tread meant replacement time. I do NOT recommend that a novice or even intermediate driver go to something like NT01, Cup 2, or even RE-71R since that seems to be similar to Cup 2 even though it's classified as Extreme Summer, and many DE organizers won't allow less experienced drivers to run such tires anyway.

No way you incluce RE71R as tires an intermediate driver should not be driving on. They are talkative and don't mask driver mistakes.