tire analysis for high speed road racing
Oct 13, 2011 17:01:52 GMT -5
Post by sigmfsk on Oct 13, 2011 17:01:52 GMT -5
This is more of an "analysis example", rather than a "modification". But it could be titled: how to modify your monaco so that the tires are accepted for high-speed road racing, such as:
www.texasmile.net/
www.ecta-lsr.com/
www.sscc.us/
"Y" rated tires are tested to 186mph.
"(Y)" rated tires are tested over 186mph, but there is no set standard so race organizations must rely on the tire manufacturer to provide that information--and most won't.
Goodyear Land Speed racing tires
www.racegoodyear.com/tires/pdf/drag_front_runner.pdf
are not approved, because they're not designed for going around turns nor for running for extended periods of time.
Michelin says they test their Pilot Sport PS2s to over 220mph, so these tires are legal for racing at those speeds.
That's what this guy used:
from
www.chevyhiperformance.com/eventcoverage/0903chp_1966_chevy_chevelle_silver_state_classic_challenge_drive/photo_06.html
The problem for those tires is the load ratings.
According to the Silver State Classic guys, a 1974 Dodge Monaco that originally came with a 440 was spec'd for H rated tires. And this does seem to correlate with the information in the owner's manual (about the wider 6.5" rims having H rated tires). So despite the fact that my B pillar has a sticker showing a minimum of G tires (load range B), I need to meet the load rating of H rated tires (load range B).
************
note. I talk a bit about this here:
bluesmobiles.proboards.com/index.cgi?action=gotopost&board=details&thread=245&post=1349
It looks like a 440 without A/C actually had a G tire rating. A 440 with A/C had an H tire rating. So my car came without A/C, but since I'm installing an A/C, it's reasonable that they want an H rating. And it doesn't matter if it's reasonable - it's the rule.
************
The Police Pursuit radials that were on the car when I got it are H rated tires, listed on the tire as a max load rating of 1770 lbs.
The Tire & Rim Association's current yearbook doesn't show the old-school load ratings, but the books from the '80s do. This page shows that a H rated tire, load range B, has a max load of 1770 lbs.
i955.photobucket.com/albums/ae40/sigmfsk/aa111013/tirechart.jpg
So I must have a tire that has a load rating (at speed) of 1770 lbs. It turns out that at 186 mph, the load rating of a tire is only 85% of its max load rating.
This page shows the reduction for Michelin
Pilot Sport PS2 | Michelin Tires
www.michelinman.com/tire-selector/name/pilot-sport-ps2-tires
Here's the reduction for Pirelli
Tyres Load and Load Capacity - PIRELLI TYRE
www.pirellityre.com/web/technology/about-tyres/tyre-function/load-load-capacity/default.page
and for all tires in general
Tire Tech - Air Pressure/Load Adjustment for High Speed Driving Z-Speed
www.tirerack.com/tires/tiretech/general/airpress_loadadj_Zspeed.jsp
so I need a tire with a max load rating of 1770 lbs / 0.85 = 2083 lbs.
This page
Tire Tech Information - How to Read Speed Rating, Load Index & Service Descriptions
www.tirerack.com/tires/tiretech/techpage.jsp?techid=35
shows that this equates to finding a tire with a load rating >= 106.
Looking at the Michelin Pilot Sport PS2, they only have one tire with a load rating >= 106
335/35ZR17
from
www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Pilot+Sport+PS2
Man, that's too wide to have on a Monaco, especially for a front tire.
Tire rack doesn't allow one to search for tires with a minimum load rating, but this site does:
Discount Tires, Cheap Tire, Michelin Tires, Cooper Tires, Falken Tires
www.discount-tires-2go.com/
Just do a search for "106Y" or "106 Y", for 106 load rated tires at the Y speed range.
This is my summary of how people seem to think various tire sizes ook on a blumo:
225/70/15 27.402" tolerable
235/70/15 27.953" good
235/75/15 28.878" great
So I'm looking for around a 28.9" diameter tire.
Some searching for 106+ load rating tires of that diameter, with a small width, yields these tires:
GDY-709613154 - Goodyear Tires EAGLE F1 GS D3 255/55ZR18 109 Y XL VSB
YT-10177 - Yokohama Tires ADVAN SPORT 255/55R18 109Y BW A/S
MICH-91991 - Michelin Tires LATITUDE SPORT 255/55R18 BSW 109 Y
PIR-1363000 - Pirelli Tires PZero Rosso Asimmetrico 255/55ZR18 109Y
BT-149974 - Bridgestone Tires TURANZA ER30 255/55R18 109Yxl BW A/S
BT-067890 - Bridgestone Tires DUELER HP SPORT 255/55R18 109Yxl BW A/S
3546590000 - Continental Tires ContiCrossContact UHP N1 255/55R18 109Y BSW XL
A 255/55R18 tire is the narrowest tire that's Y-speed rated with a load rating of at least 106. And it's the same diameter (29.0") as a 235/75R15 tire (28.9")
There's just no way around it - these tires won't look stock. So if I have these crazy tires just for racing, I might as well not worry about what the wheels look like. The cheapest and safest wheel solution seems to be custom wheels from these guys:
RACING WHEELS, ROCKCRAWLER, OFF ROAD,BEADLOCK WHEELS, THE BEST KEEPS GETTING BETTER BUY MRW
www.mrt-wheels.com/
that I learned about from this page:
Construction of my Bonneville Lakester- page 11
purplesagetradingpost.com/sumner/bvillecar/construction%20page-11.html
that also points out that the wheels
> ...are welded all the way around the attachment between the rim and the center
> section on the inside. That meets the [Bonneville land-speed-racing] rule requirements.
And that also seems to meet the Maxton Mile rule for wheels > 17" diameter:
> wheels must be manufactured for racing purposes or reinforced as follows: By welding
> the entire area of attachment between the rim and the center section...
ECTA Rules
www.ecta-lsr.com/rules/carstreetcat.htm
255/70R15 (29.1" diameter) : around-town driving
255/55R18 (29.0" diameter) : racing
The diameter is almost the same as stock, but the tires will be an inch wider than stock. I like the plan to have the same width/diameter tires for around town as for racing (although the wheel diameter is different), because I'll have plenty of lead-time to see if anything rubs or if there are any problems.
majority of post from archived info here:
www.bluesbrotherscentral.com/forum/topic/7629-z-rated-tire-wheel-questions/page__p__109005__hl__pressure__fromsearch__1#entry109005
www.texasmile.net/
www.ecta-lsr.com/
www.sscc.us/
"Y" rated tires are tested to 186mph.
"(Y)" rated tires are tested over 186mph, but there is no set standard so race organizations must rely on the tire manufacturer to provide that information--and most won't.
Goodyear Land Speed racing tires
www.racegoodyear.com/tires/pdf/drag_front_runner.pdf
are not approved, because they're not designed for going around turns nor for running for extended periods of time.
Michelin says they test their Pilot Sport PS2s to over 220mph, so these tires are legal for racing at those speeds.
That's what this guy used:
from
www.chevyhiperformance.com/eventcoverage/0903chp_1966_chevy_chevelle_silver_state_classic_challenge_drive/photo_06.html
The problem for those tires is the load ratings.
According to the Silver State Classic guys, a 1974 Dodge Monaco that originally came with a 440 was spec'd for H rated tires. And this does seem to correlate with the information in the owner's manual (about the wider 6.5" rims having H rated tires). So despite the fact that my B pillar has a sticker showing a minimum of G tires (load range B), I need to meet the load rating of H rated tires (load range B).
************
note. I talk a bit about this here:
bluesmobiles.proboards.com/index.cgi?action=gotopost&board=details&thread=245&post=1349
It looks like a 440 without A/C actually had a G tire rating. A 440 with A/C had an H tire rating. So my car came without A/C, but since I'm installing an A/C, it's reasonable that they want an H rating. And it doesn't matter if it's reasonable - it's the rule.
************
The Police Pursuit radials that were on the car when I got it are H rated tires, listed on the tire as a max load rating of 1770 lbs.
The Tire & Rim Association's current yearbook doesn't show the old-school load ratings, but the books from the '80s do. This page shows that a H rated tire, load range B, has a max load of 1770 lbs.
i955.photobucket.com/albums/ae40/sigmfsk/aa111013/tirechart.jpg
So I must have a tire that has a load rating (at speed) of 1770 lbs. It turns out that at 186 mph, the load rating of a tire is only 85% of its max load rating.
This page shows the reduction for Michelin
Pilot Sport PS2 | Michelin Tires
www.michelinman.com/tire-selector/name/pilot-sport-ps2-tires
Here's the reduction for Pirelli
Tyres Load and Load Capacity - PIRELLI TYRE
www.pirellityre.com/web/technology/about-tyres/tyre-function/load-load-capacity/default.page
and for all tires in general
Tire Tech - Air Pressure/Load Adjustment for High Speed Driving Z-Speed
www.tirerack.com/tires/tiretech/general/airpress_loadadj_Zspeed.jsp
so I need a tire with a max load rating of 1770 lbs / 0.85 = 2083 lbs.
This page
Tire Tech Information - How to Read Speed Rating, Load Index & Service Descriptions
www.tirerack.com/tires/tiretech/techpage.jsp?techid=35
shows that this equates to finding a tire with a load rating >= 106.
Looking at the Michelin Pilot Sport PS2, they only have one tire with a load rating >= 106
335/35ZR17
from
www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Pilot+Sport+PS2
Man, that's too wide to have on a Monaco, especially for a front tire.
Tire rack doesn't allow one to search for tires with a minimum load rating, but this site does:
Discount Tires, Cheap Tire, Michelin Tires, Cooper Tires, Falken Tires
www.discount-tires-2go.com/
Just do a search for "106Y" or "106 Y", for 106 load rated tires at the Y speed range.
This is my summary of how people seem to think various tire sizes ook on a blumo:
225/70/15 27.402" tolerable
235/70/15 27.953" good
235/75/15 28.878" great
So I'm looking for around a 28.9" diameter tire.
Some searching for 106+ load rating tires of that diameter, with a small width, yields these tires:
GDY-709613154 - Goodyear Tires EAGLE F1 GS D3 255/55ZR18 109 Y XL VSB
YT-10177 - Yokohama Tires ADVAN SPORT 255/55R18 109Y BW A/S
MICH-91991 - Michelin Tires LATITUDE SPORT 255/55R18 BSW 109 Y
PIR-1363000 - Pirelli Tires PZero Rosso Asimmetrico 255/55ZR18 109Y
BT-149974 - Bridgestone Tires TURANZA ER30 255/55R18 109Yxl BW A/S
BT-067890 - Bridgestone Tires DUELER HP SPORT 255/55R18 109Yxl BW A/S
3546590000 - Continental Tires ContiCrossContact UHP N1 255/55R18 109Y BSW XL
A 255/55R18 tire is the narrowest tire that's Y-speed rated with a load rating of at least 106. And it's the same diameter (29.0") as a 235/75R15 tire (28.9")
There's just no way around it - these tires won't look stock. So if I have these crazy tires just for racing, I might as well not worry about what the wheels look like. The cheapest and safest wheel solution seems to be custom wheels from these guys:
RACING WHEELS, ROCKCRAWLER, OFF ROAD,BEADLOCK WHEELS, THE BEST KEEPS GETTING BETTER BUY MRW
www.mrt-wheels.com/
that I learned about from this page:
Construction of my Bonneville Lakester- page 11
purplesagetradingpost.com/sumner/bvillecar/construction%20page-11.html
that also points out that the wheels
> ...are welded all the way around the attachment between the rim and the center
> section on the inside. That meets the [Bonneville land-speed-racing] rule requirements.
And that also seems to meet the Maxton Mile rule for wheels > 17" diameter:
> wheels must be manufactured for racing purposes or reinforced as follows: By welding
> the entire area of attachment between the rim and the center section...
ECTA Rules
www.ecta-lsr.com/rules/carstreetcat.htm
255/70R15 (29.1" diameter) : around-town driving
255/55R18 (29.0" diameter) : racing
The diameter is almost the same as stock, but the tires will be an inch wider than stock. I like the plan to have the same width/diameter tires for around town as for racing (although the wheel diameter is different), because I'll have plenty of lead-time to see if anything rubs or if there are any problems.
majority of post from archived info here:
www.bluesbrotherscentral.com/forum/topic/7629-z-rated-tire-wheel-questions/page__p__109005__hl__pressure__fromsearch__1#entry109005