Full Report: Road & Track tests stickier FR-S/BRZ tires

[Matador]

^^weights of said wheels (18")?

[Lasse]

Originally Posted by brianc

It was a MazdaSpeed 3 wasn't it? 280lbs of tq go a long way.

There is actually a track review coming out of the new Genesis 2.0T R Spec vs the 2013 Scion FR-S. I was at the track when they filmed it. The Genesis consistently got faster lap times than the FR-S.

Hmmm, yeah. If you watch the video, you notice that Scion jumps from slowest to fastest just changing tires. This thing is "fast" with grippier tires. I don't know is it faster than genesis coupe, and i don't even care. But i know that tire cost of this vehicle are very reasonable! You can buy new set of tires with reasonable price and still be fast, you cant do that with r-spec GC

[brianc]

Originally Posted by Matador

^^weights of said wheels (18")?

17x7.5 with star spec z1s vs 17x9.5 with star spec z1s. Same alignment front and rear. The wider tire got .5 of a second slower every lap in a 1 minute track. I was driving. The wider tire wouldn't allow the rear to turn over. The car was understeering. This was a fwd though.

[rice_classic]

Originally Posted by brianc

It's not surprising a wider tire would yield slower lap times. I've noticed this on the track myself for 200hp cars. There just isn't enough power to justify a wider tire. The tires need to give a little bit for proper steering.

There may have been other factors at play. More mechanical grip almost always improves lap times. If you're putting wider tires on your car (within reason), of the same brand/type and maintaining the same rolling diameter and getting slower lap times then something else needs to be addressed.

[Matador]

Originally Posted by brianc

17x7.5 with star spec z1s vs 17x9.5 with star spec z1s. Same alignment front and rear. The wider tire got .5 of a second slower every lap in a 1 minute track. I was driving. The wider tire wouldn't allow the rear to turn over. The car was understeering. This was a fwd though.

Sorry, was referring to the poster before you.

[sickmint79]

i plan on enkei rpf1 17x7.5 with 225s. good footprint and stick and light weight. 18s are 2.4 lbs more apiece of rotational mass... plus extra weight for that 18" tire... is the 18 really going to be moar fastars? i'm speculating no.

[Bu-Tang]

this has been reposted twice now

[empower-auto]

So, to get past 1.0G .. tires and ______

[vtmike]

It's not the width but the diameter that slows it down. The wider tires were 18's. Interestingly the wider 18's had more grip but slower lap times. Would have been interesting to see the results of lighter wider 17" wheels with the 235 tires.

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[MmmHamSandwich]

Originally Posted by Lasse

But i know that tire cost of this vehicle are very reasonable!

This. 215/45/17 is a great size for selection and price. Upsizing to 18 alone typically adds 25% right off the bat.

[Sasquachulator]

i thought the point of the OEM tires was so it was easy to throw the back end out for a drift.

So the 18's they used were not ideally sized to match the stock size?

Ideally you'd want to match the stock rolling diameter as close as possible...cuz you'd end up with either an incorrect speedometer or you'd have to recalibrate the speedometer to match the new tire size.

[#87]

Originally Posted by Sasquachulator

i thought the point of the OEM tires was so it was easy to throw the back end out for a drift.

So the 18's they used were not ideally sized to match the stock size?

Ideally you'd want to match the stock rolling diameter as close as possible...cuz you'd end up with either an incorrect speedometer or you'd have to recalibrate the speedometer to match the new tire size.

Yes the diameter is off but the major con is not the speedo, who really cares about that anyway? It's the slight alteration to the gearing.

[demby123]

Now if only we could see the results with lightweight 16s and the same tire

[Allch Chcar]

Originally Posted by rice_classic

There may have been other factors at play. More mechanical grip almost always improves lap times. If you're putting wider tires on your car (within reason), of the same brand/type and maintaining the same rolling diameter and getting slower lap times then something else needs to be addressed.

You can see that it slowed acceleration going to the wider tires. They use G-meters to monitor acceleration and grip.

I've seen this same phenomenom in Forza (they use a good tire physics system) so I'm not surprised.

Plus it just makes sense, unsprung rolling mass is multiplied compared to sprung mass. Plus bigger tires have more rolling resistance. On modest HP, it makes a significant difference.