Street Tire Choice

MikeBrally

Registered User
I have a 1997 Thunderbird with a TVS2300-blown big bore 2V modular. The combo makes 560 RWHP and 520 RWTQ. Rear tire size is limited to 285 width by the wheel wells, and I'm running a 285/40-18 on a 10" wide rim. Originally tried Nitto NT555 G2s all around on the street, but traction was nonexistent. After switching to NT555Rs on the back, the car was much more manageable. The tread depth is down substantially after about 6,000 miles, so I'm looking to replace them. My question is whether to just get another set of NT555Rs, or switch to the newer NT555R2. On paper, the newer tire looks more desirable, but I'm concerned about the lower load index (96 versus 101 for the R). My car weighs about 3900#, and when we road trip it with luggage, tools and two aboard it maxes out between 4400 and 4500#. Would the 96 load index be sufficient? Also, what experiences have people had with the NT555R2, good or bad?
 

David Neibert

SCCoA Admin
The 555R2 is supposed to be the same compound as NT05R tire and should perform better as far as traction on the track goes, but doubt it is any better on the street than the 555R you have now. I'm thinking about putting a set of the 555R2 tires on my Hellcat 18" race wheels to use on Hot Rod Drag week. Don't know anyone in this club who has used them, but several of the Hellcat guys have tried them and are giving mixed reviews with most saying they aren't much different than the 555Rs


David
 

AdamG

SCCoA Member
I'm running continental extreme contact sports on mine and actually got enough grip with them to snap an axle at the track last year. I had Goodyear eagle f1 supercar before these and the continentals grip so much better. I've been very satisfied with them since I switched to them last summer. They have the 101 rating as well.
 

neverfastenough

Registered User
I have a 1997 Thunderbird with a TVS2300-blown big bore 2V modular. The combo makes 560 RWHP and 520 RWTQ. Rear tire size is limited to 285 width by the wheel wells, and I'm running a 285/40-18 on a 10" wide rim. Originally tried Nitto NT555 G2s all around on the street, but traction was nonexistent. After switching to NT555Rs on the back, the car was much more manageable. The tread depth is down substantially after about 6,000 miles, so I'm looking to replace them. My question is whether to just get another set of NT555Rs, or switch to the newer NT555R2. On paper, the newer tire looks more desirable, but I'm concerned about the lower load index (96 versus 101 for the R). My car weighs about 3900#, and when we road trip it with luggage, tools and two aboard it maxes out between 4400 and 4500#. Would the 96 load index be sufficient? Also, what experiences have people had with the NT555R2, good or bad?

I've had nitto nt05, multiple different mickey, Hoosier and m&h on my bird. 700+whp. Hands down, and I mean hands down, the m&h Dr absolutely mopped the floor with the others. If I was in the market for a street DR I wouldn't consider anything else.
 

MikeBrally

Registered User
neverfastenough,

Thanks for the feedback. M+H doesn't offer a 27" diameter tire to fit an 18" diameter wheel (what I have now), but they do offer a 28" diameter tire that might work. Have you driven the M+H DR on the street? In the rain?
 

neverfastenough

Registered User
neverfastenough,

Thanks for the feedback. M+H doesn't offer a 27" diameter tire to fit an 18" diameter wheel (what I have now), but they do offer a 28" diameter tire that might work. Have you driven the M+H DR on the street? In the rain?

Typo above I ran the nt05r not the regular.

As for rain I had the nt05r in rain, not bad, mickeys bias ply et Street in Rain was similar to in snow. Mickey et Street radial, still very bad in rain. Hoosier never in rain, m&h never in rain. I think the m&h would be safe at city speeds in rain and 55mph hw carefully
 

MikeBrally

Registered User
What I have liked best about the NT555Rs is that they can be driven like a high performance summer tire, with no problems in rain. And, other than tread life, they have held up well to heavy load, long trips and high speeds. The NT555R2 may be as good or better, which is why I've posted a few places asking about people's experiences with them.

I've been trying to talk to somebody at Nitto about the load index concern, but never get through to a person. And, they haven't answered the email I sent last Monday.
 

MadMikeyL

SCCoA Member
A load index of 96 means it can support 1565lbs per tire. A 101 can support 1819lbs per tire. Assuming 50% weight over the back tires at 4500lbs, that is only 1125lbs per tire, so well under the capability of the tire. Where the problem comes in is that the load index is based on maximum tire pressure, which presumably you are not running. With the lower index, you may have to run a higher tire pressure, which of course is going to hurt the tire’s ability to hook. All the reviews of the r2s are very favorable, so I would probably try them, and just bump the pressure up a bit when you are loaded up for road trips and see how they do. Also consider this; the 205/70/15s that would have come stock on a base model Tbird only had a load index of 95, so while the 96 is lower than what you have been running, it is still higher than the car’s original spec.
 

RalphP

SCCoA Member
To amplify MadMikeys' comments, you can find load / PSI tables on the Internet for most sizes of tires.

Here's one that works for most usages:

https://www.bfgoodrichtires.com/on/...Size/420bcacc-01bf-42c9-840e-55344685c842.pdf

Take the original size and pressure; find that; look for what pressure supports the same weight at the new tire size; and you should be OK.

If the car has been lightened or weighed down, figure that in too (for instance, if you load 800 pounds into the trunk, that's nominally 400 pounds per tire - add 400 pounds to the OEM rating, then find that pressure.)

And for optimal gas mileage on a trip, you can usually bump it 2 to 4 PSI cold as long as you don't exceed the tire's rating.

(For maximum traction in racing, you'd probably want to drop it a bit; how much, I dunno. I don't race, so that's black magic to me at this point, not being something I have studied or worried about. Others can chip in on that part.)

RwP
 

MikeBrally

Registered User
Mikey and RalphP,

Thanks for the good review of the basics! Your posts got me thinking about load distribution and actual tire loading versus ratings. So, engineer that I am, I dug into the numbers.

An old post on TCCoA lists the weight distribution of a stock ’96 LX 4.6L Sport as 58%/42%, which is quite a bit more uneven than I would have guessed. Another source put the dry weight of a ’97 LX 4.6L at 3644#. My very much non-stock ’97 weighs 3880# with gas, and I think the 58/42 split would still be in the ballpark. That is 1125# per tire in front and 815# per tire in back.

When we road trip, we add 350# of passengers in the middle of the car, and 250# of luggage and tools at the back. Splitting the passenger weight, and adding the other weight to rear only, puts the tire loads at about 1215# front and 1035# rear. That actually improves weight distribution to about 54%/46%.

My car came with 225/60-16 tires, which I ran at 30 PSI. That gave a load capability of 1477#, per the chart. I run the current 255/45-18 front and 285/40-18 rear tires at 35 PSI, which gives 1433# front and 1565# rear capability (assuming 96 load index). So, that gives about the same capability as stock at the front, and somewhat more at the rear for the current setup. And pretty good margins above actual loading, especially at the rear.

Bottom line: I should be able to run the NT555R2s on the rear with confidence. Thanks for helping me see the way to that conclusion!
 
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MikeBrally

Registered User
neverfastenough,

I talked to the Tech guy at M+H this morning, and he said their drag radial is absolutely NOT intended for long distance driving or use in the rain.
 

neverfastenough

Registered User
neverfastenough,

I talked to the Tech guy at M+H this morning, and he said their drag radial is absolutely NOT intended for long distance driving or use in the rain.


Well I get the rain part, they have to cover their butts from a liability standpoint. Long distance I don't really understand. I did a 300mi round trip run with dyno time included and the tires still had titties on them when I got home.

Tires should inspire confidence, buy what makes you feel best. I wanted dry grip. Had it rained on the way home I wouldn't have freaked out. 90% of the internet also claims you'll immediately die and burst in to flames if you drive a bias ply on the street as well, and I've done that for years and currently still do.
 
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