Datsun Roadster Forum-311s.org

We drive our roadsters in the rain-- it's just a reality of living in Oregon-- at some point you're gonna run into weather. Top up, top down, it does not matter much, our wipers work and everything...



But I feel that perhaps this warrants a special edition t-shirt!



-m

Redroadster,

Regarding your original point, (ceteris paribus) "Wide tires are particularly susceptible to hydroplaning."

https://www.springer.com/cda/content/do ... p176308738

That said, you will NEVER hear the following words spoken in Texas:

"Them truck tires is too big!"

Jon

I LOVE the lightweight R16 feel of the SR20 @ triple the hp.
I just run low air pressure. No problems.
My U20 car is @28F and 26R w/195/50/16s.
R16 car is 27F and 24R w/185/65/15s.
Ted and I were SHREDDING roads last week. I know right?!?! Proof; he wasnt complaining about how slow I was driving lol.

jhayden wrote: ↑Sun Feb 03, 2019 8:58 pm Redroadster,

Regarding your original point, (ceteris paribus) "Wide tires are particularly susceptible to hydroplaning."

https://www.springer.com/cda/content/do ... p176308738

That said, you will NEVER hear the following words spoken in Texas:

"Them truck tires is too big!"

Jon

I guess it goes back to all things in moderation. You want a lot of rubber contacting the road with a dry clean surface but you don't if there is water or gravel on the surface of the road. Slick times give a lot of rubber to road but cutting tread gives water a place to go so as to avoid hydorplaning.
Somewhere in teh middle of all that is the best tire.
This has been an intresting brain puzzle but can you vary the width of the tires significantly without modifying the car?

Just to interject ...1 last time
This was the car going at normal speed limit 45, in summer
Around a gentle to medium R arc , when it experienced a medium plow condition , on a dry road that may have had a film of humid air coating it or pollen from a tree he just past .
I think the big ? Is what would it done with oem wheel and tires .
I drove mine with 4,80 s for 3 months , I drove it hard around turns to see if it started to slip , only a bit
But once turning somewhat normal I failed to see sand grit in the road, it slipped 3ft ,but then bit hard .
I drove this same road with the other wider wheels ,and once it slipped and just caught before going off the L side

Daryl Smith wrote: ↑Sun Feb 03, 2019 2:57 pm "A week later Datsun had a 2 page stapled info sheet that we were to give to roadster owners and 240Z owners telling of possible slipping on such a road from the aftermarket wider tires and wheels , there is a much less downforce per square inch from the original narrow tires. "The ONLY instance I can think of where a narrow (as defined by "original tires") would be helpful would be gas milage.

Also snow.. You want narrow tires on snow.

There are a lot of reasons a car could decide to lose control, but 2 sizes over on the tires is not one of them.

If you were running 11 inch wide tires like are on my race car, then there are some decisions you need to make with the suspension. But taking it out to a 205 or something and somehow this caused a sudden loss of control due to less downforce? I am just not a believer.

185 narrow enough?
.

redroadster wrote: ↑Fri Feb 01, 2019 8:45 pm I think it should be taken into account when building some of the rides here ...sr20 ...etc

Why do you mention SR20?

RCMike wrote: ↑Sat Feb 09, 2019 4:46 am 205 or something and somehow this caused a sudden loss of control due to less downforce? I am just not a believer.

+1

I would be more concerned with OLD tires on our roadsters.

Since the weight of the vehicle is going to determine the area of the tires contact patch, both tires will see the same amount of square inches dispersed on the road. The difference will be that the skinny tire will have a long skinny patch while the fat tire will have a short wide patch. As most of our roads are not perfectly flat, theoretically a bump could cause the fat tire to loose its thin contact patch easier than the skinny tires long contact patch. Doubtful, that it's going to make you loose control unless you are already teetering on the extreamly limit of adhesion!

This thread is exhausting. If I’m teetering and out of control I call Uber. Just saying.
Keith

Perhaps it's time to come to a screeching halt

RCMike wrote: ↑Sat Feb 09, 2019 4:46 am

Daryl Smith wrote: ↑Sun Feb 03, 2019 2:57 pm "A week later Datsun had a 2 page stapled info sheet that we were to give to roadster owners and 240Z owners telling of possible slipping on such a road from the aftermarket wider tires and wheels , there is a much less downforce per square inch from the original narrow tires. "The ONLY instance I can think of where a narrow (as defined by "original tires") would be helpful would be gas milage.

Also snow.. You want narrow tires on snow.

There are a lot of reasons a car could decide to lose control, but 2 sizes over on the tires is not one of them.

If you were running 11 inch wide tires like are on my race car, then there are some decisions you need to make with the suspension. But taking it out to a 205 or something and somehow this caused a sudden loss of control due to less downforce? I am just not a believer.

It automotive Engineering ....you wouldnt understand

About time to close up this thread. Notoptoy? Garth? Are you guys on duty.

Ted

ted heaton wrote: ↑Sat Feb 09, 2019 11:33 pm About time to close up this thread. Notoptoy? Garth? Are you guys on duty.

Ted

No, No, No! Before it gets closed...Redroadster please tell us why your roadster is jacked up in the rear, for us Non-Automotive Engineering types