Swanpuppy

Quick question for guys with the Spec Miata take off tires: Are you able to run the SM6 or SM7 on the street to and from events? I dont think they are technically legal on the road, I just mean is it going to be like driving on wooden wheels on the highway or is it feasible? I do not have a trailer but might have a way to snag a set of hoosiers to try out this season.

cabowabo

As long as there's no standing water see no reason why you can't. I've driven RC-1's to the track (~2 hours) and around town a handful of times. The only problem is rcomps are less puncture resistant from what I understand.

Swanpuppy

It seems most SM7 tires are considered DOT rated, so technically they can be on the road from what I'm seeing. Unless this is inaccurate I answered my own question. Thanks for the tipcobowabo.

sixshooter

iTrader: (12)

They are DOT rated but say for competition use only on the sides.

They heat cycle every time you use them so they are terrible to use on the street. If they are already heat cycled a couple of times before and you use them for a commute for a few days they have lost 80% of whatever made them special versus a performance street tire. They get harder quickly. If they freeze they are ruined.

My SM7 takeoffs have also done an entire track weekend as well as a SM race so test driving across town yesterday to check fitment and feel once wasn't a big deal. They're already a shadow of their former selves.

Swanpuppy

The SM takeoffs, I assume most people are getting these with 4-6 heat cycles or so on them. I have read that life expectancy is maybe 8-10? Does that sound right? So does that mean you're only getting 1-2 weekends of HPDE (3 sessions each) max out of a full set before you need to swap another set on? It might not even be worth me getting these if a full set only lasts a weekend or so.

cabowabo

For HPDE you should get fresh RC1/NT01 and be done with it. I just got fresh SM7's for NASA TT, but am only going to run them 1-2 sessions per day hunting time, then swapping back to RS4's to keep HC's off the SM7s. A buddy ran SM7 take off's on his kswap a couple of events ago and was slower than on his 225 (possibly 245?) RC1's.

sixshooter

iTrader: (12)

Hmmm. NASA Florida gives six 20min and two 25min sessions a weekend, or about 2 3/4 hours. Performance Driving Group gives 6 30 minute sessions in one day and then sometimes some open lapping at the end of the day, so 3+ hours. That's a pretty good day for one set of tires. I usually bring a couple of spare sets to the track in case of a flat spot, a puncture, or a bent wheel. Usually doesn't happen but nice to have spares. But, yeah, performance does fall off.

Oh4One4

When I worked for a Spec Miata team we cycled out tires anywhere from 3-6 hours of use depending on the driver. Though it would be legal to drive SM7's on the street, if your event is two hours away and the tires had 5 solid heat cycles on them already, they would be completely toast by the time you got to your event, and I wouldnt trust them to hold air on the way back home.

Swanpuppy

Ok, this makes more sense. People are able to get about 3 hours of track time on a set of take offs, give or take. In the Milwaukee region our HPDE are 3 20 minute sessions for an hour total. So if the tires are swapped at the event, I SHOULD be able to squeeze 2, maybe 3 events out of a set before they are garbage. And driving them on the street destroys them. Got it.

This is good info. Makes the decision if its worth getting a set to try or not easier, vs just running a sticky street tire. Thanks all.

scenturion

iTrader: (9)

FWIW I recorded tire temps with a pyrometer after 3+ hours of highway driving on NT01s and the tire temp didnt get above ~90degF in 80ish degF ambient. I'm not convinced you could heat cycle tires just with normal highway driving.

Swanpuppy

I currently run Federal 595RS-RR tires on my 15x9 wheels on the street. I maybe put on 3k miles a year, so daily driving these and doing track days (5 a year) isn't outrageous, I should get 2-3 years out of a set. I just dont know if it makes sense to go after slicks for HPDE just to shave a few seconds and deal with hauling tires/swapping every event. I do have a spare set of rims, but the pay off doesnt seem to be there.

sixshooter

iTrader: (12)

Doesn't sound worth it for you.

To my understanding it is cycles and not actually usage time that Harden of the rubber and cause the tire to be less grippy. This seems to be the case in my experience as well as what I have read.

Leveq

If you're just doing track days probably not. Timed events are another thing.