Tires, Boxster, best Bang for the buck & size

[pk2]

Hello,

I’ve got a 99 Boxster with 18 ’inch factory turbo twists wheels, zr 265/35 18’s on the back and the complimentary zr 225/40 up front. Bout ready for some new rubber.

Don’t drive too hard or race, but like the twisssties. Can’t go very fast around here, 120 the most I’ve been (if that fits into the equation). Also like longevity, and price big (trade price and life for a little less performance). Votes for the best bang for the buck… size, brand?

Votes are appreciated…

P.K.

[fastboydave]

There's been alot of discussion about this and the name that crops up is Kuhmo tyres. Some people rate them, others do not (like any brand of tyre), but as they are considerably cheaper, if you arent bothered about the "N" rating and only drive it 'everyday' etc, maybe these are the way to go?

[rsfeller]

Khumo, Khumo, Khumo and the 4th wheel I'd put another Khumo on...

P.K.

[hooster]

Definitely Kuhmos. Go to Tirerack.com and get them for like $90ish a piece. Try the ECSTA ASX for all-season performance. I've had these for over a year now and love them. You'll immediately notice a stiffer feel, but after a few days you don't notice that anymore. The speed (Z), strength (AA?), and tread (440) ratings are all superior or the same as the OEM Michelins. Actually, the treads are 2x the rating. Barring nails or other hazards, should be able to get great mileage even if you are autocrossing. They also look very nice.

[rsfeller]

I agree on the tread wear. I have 15K on mine and they are yet to show much wear. For daily fun driving and needing all-season dependablity go with the Kumhos. I got mine at tirerack.com. Next day delivery but I'm a state away.

Get them mounted and balanced ONLY on a Hunter road force tester. You'll be happy you did...

[pk2]

Definitely Kuhmos. Go to Tirerack.com and get them for like $90ish a piece. Try the ECSTA ASX for all-season performance. I've had these for over a year now and love them. You'll immediately notice a stiffer feel, but after a few days you don't notice that anymore. The speed (Z), strength (AA?), and tread (440) ratings are all superior or the same as the OEM Michelins. Actually, the treads are 2x the rating. Barring nails or other hazards, should be able to get great mileage even if you are autocrossing. They also look very nice.

Thanks, Kinda made up my mind on Kumhos. Oddly, general tires seems to lead the pack (tire rack rankings) for less, but they don't have the right size for the rear.

Thanks, PK

Edited October 1, 2007 by pk2

[jmatta]

I have Kuhmo Ecsta MXs on my '02 Boxster S. Great dry weather grip, though they are not for wet. My car is not a daily driver though.

[mikefocke]

Tires are the only thing you have to contact the road

and help you turning and stopping.

I'd refer you to the November issue of Consumer Reports where their tests of High Performance Tires in 10 categories of performance showed the Kumho Ecsta SPT's to be significantly inferior in both wet braking and wet handling to higher rated tires.

In a situation where 10 feet can make the difference between stopping safely and a serious fender-bender, do you really want to save the $ and create that risk? Only you can answer that question for yourself. Maybe because fo your geography it isn't important to you. But if you take your Boxster out in the rain, statistics could catch up with you.

More Info Here including the ratings on a few of the more common Boxster tires.

[simbob]

Mike,

Thanks for your post and the link to your Boxster tire guide.

I have a 1999 Boxster with the Sport Package, so it has the Boxster Design 17" wheels, with 205/50-17 front tires and 255/40-17 rears. When I bought it in August, it had new Fuzion ZRi's on the back and relatively older Bridgestone Potenza S-02's on the front. The fronts will require replacement much sooner than the rears, and I would like to match the new fronts to the rears, but I would prefer not to discard the two rear tires when they still have a lot of life left. In addition, the ZRi (made by Bridgestone) is roughly $100 per tire, while the S-02 is over $200 per tire.

Unfortunately, it appears that Fuzion does not make a 205/50-17 ZRi. They do make a 205/40-17 and a 215/50-17. Is either of these "off-size" tires an acceptable alternative on a Boxster? Or am I better off buying S-02's for the front, living with different tires front and rear until the rears need replacing, and then matching front to rear by going back to S-02's for the rear? Or, is there another tire which would be better on the front for now which I could match on the rear later?

I'm not inclined to buy off-size tires because of their effect on handling and braking, and buying the off-size Fuzion will commit me to the same problem for a longer term if they continue to be unavailable in the correct size for the front.

If I'm doing the math correctly, the 205/40 tire has a diameter of 23.45 inches, and the 205/50 has a diameter of 25.07 inches (a difference of 1.62 inches). The ride height difference will be .81 inches. I would expect that lowering the nose by close to an inch and increasing the rotational speed of the front tires would have an effect on handling and braking (maybe including the functioning of the ABS), so I'm not inclined to use a the 205/40 tire.

The 215/50 tire creates less of a diameter, ride height and rotational differential (diameter .39 inches larger, ride height .195 inches higher) and would seem to have less of an effect on handling and braking -- maybe negligible. On the wider tire, I am concerned about the dynamics with the rim and the effect on the shape of the sidewall.

Although I am a former SCCA racer, I have no intention of using the car for track days or club racing, and even autocross is unlikely. It will be daily transportation shared by my wife and me (more hers than mine, and she doesn't commute) in all weather, with some spirited back road driving in the right conditions. I'm in Charlotte, NC, so snow is unlikely to be an issue, and we have another car for the few days per year on which our climate will make driving the Boxster risky.

At this time, despite the price differential, I'm inclined to replace the fronts with the S-02 in the correct size and then replace the rears with S-02's when they are ready. I know you have expressed a preference for Michelins. Do you think it would be a better choice to replace the fronts with a Michelin alternative and then match all four by replacing the ZRi's with the corresponding Michelins on the rear when the time comes?

Thanks -- and thanks to anybody else who has an opinion.

Bob

Edited October 2, 2007 by simbob

[cle1bjj]

Goodyear Eagle F1GS-D3's. I have had these on my 01 986 all season and couldn't ask for a better tire. I have these tires also on a 3 series cab and a SL500. The SL is on its 2nd set, first set ran for 30k!!! I have only used these tires in the dry and never have tracked any of these cars. These tires take whatever trouble I can get them in. I have made the SL do things I didn't think possible. Bang for the buck they are great, just check out all the reviews. The dealerships service manager asked me about them the other day and I told her the same thing. Do your homework, price is important but tires are what keeps you on the road!!! These are far from the pricest set but not the cheapest.

[pk2]

Tires are the only thing you have to contact the road

and help you turning and stopping.

I'd refer you to the November issue of Consumer Reports where their tests of High Performance Tires in 10 categories of performance showed the Kumho Ecsta SPT's to be significantly inferior in both wet braking and wet handling to higher rated tires.

In a situation where 10 feet can make the difference between stopping safely and a serious fender-bender, do you really want to save the $ and create that risk? Only you can answer that question for yourself. Maybe because fo your geography it isn't important to you. But if you take your Boxster out in the rain, statistics could catch up with you.

More Info Here including the ratings on a few of the more common Boxster tires.

Thanks for the advice,

I checked that out, bit disappointed in the kumho’s mediocre showing. However, here in the sunny south west coast we’re in the midst of the driest year on record (3/4” of rain so far) and 6 yrs into a drought. Wet performance is never really an issue, 7” or so yearly is about the max we ever get ( and I havent' seen that in 15+ yrs.).

Beside people around here cant drive; If you can make a quick stop you’ll probably just get rear-ended :) .

Thanks Again, PK

Edited October 3, 2007 by pk2

[pk2]

I agree on the tread wear. I have 15K on mine and they are yet to show much wear. For daily fun driving and needing all-season dependablity go with the Kumhos. I got mine at tirerack.com. Next day delivery but I'm a state away.

Get them mounted and balanced ONLY on a Hunter road force tester. You'll be happy you did...

THanks for the reply.

What is a Hunter road force tester and what tangible difference does it make for a daily driver?

PK

[pk2]

There's been alot of discussion about this and the name that crops up is Kuhmo tyres. Some people rate them, others do not (like any brand of tyre), but as they are considerably cheaper, if you arent bothered about the "N" rating and only drive it 'everyday' etc, maybe these are the way to go?

I mentioned 120mph, that’s on really rare occasions. Mostly if you happen to get a rare break in traffic you can hit 85-90 mph. Except for a few back-roads with some tight twisties once in awhile, the thrills come in sweeping off-ramps.

Guess my point is; there little need for prolonged high speeds.

Thanks.

PK

[macsak]

do they have a 225/45/17?

aloha

steve

Mike,

Thanks for your post and the link to your Boxster tire guide.

I have a 1999 Boxster with the Sport Package, so it has the Boxster Design 17" wheels, with 205/50-17 front tires and 255/40-17 rears. When I bought it in August, it had new Fuzion ZRi's on the back and relatively older Bridgestone Potenza S-02's on the front. The fronts will require replacement much sooner than the rears, and I would like to match the new fronts to the rears, but I would prefer not to discard the two rear tires when they still have a lot of life left. In addition, the ZRi (made by Bridgestone) is roughly $100 per tire, while the S-02 is over $200 per tire.

Unfortunately, it appears that Fuzion does not make a 205/50-17 ZRi. They do make a 205/40-17 and a 215/50-17. Is either of these "off-size" tires an acceptable alternative on a Boxster? Or am I better off buying S-02's for the front, living with different tires front and rear until the rears need replacing, and then matching front to rear by going back to S-02's for the rear? Or, is there another tire which would be better on the front for now which I could match on the rear later?

I'm not inclined to buy off-size tires because of their effect on handling and braking, and buying the off-size Fuzion will commit me to the same problem for a longer term if they continue to be unavailable in the correct size for the front.

If I'm doing the math correctly, the 205/40 tire has a diameter of 23.45 inches, and the 205/50 has a diameter of 25.07 inches (a difference of 1.62 inches). The ride height difference will be .81 inches. I would expect that lowering the nose by close to an inch and increasing the rotational speed of the front tires would have an effect on handling and braking (maybe including the functioning of the ABS), so I'm not inclined to use a the 205/40 tire.

The 215/50 tire creates less of a diameter, ride height and rotational differential (diameter .39 inches larger, ride height .195 inches higher) and would seem to have less of an effect on handling and braking -- maybe negligible. On the wider tire, I am concerned about the dynamics with the rim and the effect on the shape of the sidewall.

Although I am a former SCCA racer, I have no intention of using the car for track days or club racing, and even autocross is unlikely. It will be daily transportation shared by my wife and me (more hers than mine, and she doesn't commute) in all weather, with some spirited back road driving in the right conditions. I'm in Charlotte, NC, so snow is unlikely to be an issue, and we have another car for the few days per year on which our climate will make driving the Boxster risky.

At this time, despite the price differential, I'm inclined to replace the fronts with the S-02 in the correct size and then replace the rears with S-02's when they are ready. I know you have expressed a preference for Michelins. Do you think it would be a better choice to replace the fronts with a Michelin alternative and then match all four by replacing the ZRi's with the corresponding Michelins on the rear when the time comes?

Thanks -- and thanks to anybody else who has an opinion.

Bob

[efahl]

If I'm doing the math correctly, the 205/40 tire has a diameter of 23.45 inches, and the 205/50 has a diameter of 25.07 inches (a difference of 1.62 inches).

Just caught this thread...

There are about a million on-line calculators for tire diameter out there, I wrote one that lets you see similar sized tires and how much they vary from the nominal one in percent and speedo effect...

http://www.not2fast.com/chassis/sizing.shtml

HTH,

Eric

[simbob]

Eric,

Thanks for the calculator.

I see that the 225/45-17 has the least rolling speed differential from a 205/50-17. That would reduce any effect on ABS sensors and any gyroscopic effect on handling, but what is the effect of a 10mm tread-width increase on handling, if any? First, I understand that the standard front tire size and recommended inflation pressure on the Boxster, when paired with the wider wheel/tread, lower-profile and higher inflation pressure of the rear, is intended, along with the standard suspension and alignment settings, to reduce the tendency of the mid-rear engine, rear-drive car to oversteer. Second, what is the effect of mounting a wider than standard tire on the rim, both on the rim and on the bead and sidewall of the tire?

As I mentioned, the Boxster will be primarily my wife's car. She's a very good driver, but not trained for high performance, rear-drive handling, where the higher limits of the tires can be reached more suddenly and with less warning. Maybe we'll get her that training, but, in the meantime, I don't want to reduce the designed-in understeer safety margin of the car for her real-world driving.

At this point, after some more research, it appears to me that, among the tires theoretically available in the correct size, the Goodyear F1 GS D3 might have the least tread pattern, structure, compound, handling characteristic and wear differential with the Fuzion ZRi's on the back, so I might see if I can order a pair for the front and replace the rears with matching tires when the time comes. I have time with the existing fronts for a reasonable back order wait.

The other alternative I'm considering at this point is scrapping the Fuzions and replacing all four tires with a matched set of the relatively new Goodyear F1 All Season. This seems like it might be the safest route for my wife's daily use in a temperate 4-season climate, with winters where temperatures in the 30's are not uncommon and we have occasional ice and minimal snow.

Having lived in Salt Lake City until this summer, she's an experienced snow driver, but that was in a clapped-out Camry.

Thanks again.

Bob

Edited October 4, 2007 by simbob

[Raysgv]

Goodyear Eagle F1GS-D3's. Do your homework, price is important but tires are what keeps you on the road!!! These are far from the pricest set but not the cheapest.

I am very happy with these on my 2000, 18" wheels with sport suspension.

[macsak]

the tires and pressures are designed to increase understeer, which is safer for normal driving

225/45/17 will make the car understeer less (make it more neutral)

it may make turn-in marginally less quick, but there are lots of people who love this change

it may have a tiny effect on the bead and sidewall, but again this is not significant

that said, if you desire to keep the built-in understeer for your wife, keep the standard tire sizes and pressures

aloha

steve

Eric,

Thanks for the calculator.

I see that the 225/45-17 has the least rolling speed differential from a 205/50-17. That would reduce any effect on ABS sensors and any gyroscopic effect on handling, but what is the effect of a 10mm tread-width increase on handling, if any? First, I understand that the standard front tire size and recommended inflation pressure on the Boxster, when paired with the wider wheel/tread, lower-profile and higher inflation pressure of the rear, is intended, along with the standard suspension and alignment settings, to reduce the tendency of the mid-rear engine, rear-drive car to oversteer. Second, what is the effect of mounting a wider than standard tire on the rim, both on the rim and on the bead and sidewall of the tire?

As I mentioned, the Boxster will be primarily my wife's car. She's a very good driver, but not trained for high performance, rear-drive handling, where the higher limits of the tires can be reached more suddenly and with less warning. Maybe we'll get her that training, but, in the meantime, I don't want to reduce the designed-in understeer safety margin of the car for her real-world driving.

At this point, after some more research, it appears to me that, among the tires theoretically available in the correct size, the Goodyear F1 GS D3 might have the least tread pattern, structure, compound, handling characteristic and wear differential with the Fuzion ZRi's on the back, so I might see if I can order a pair for the front and replace the rears with matching tires when the time comes. I have time with the existing fronts for a reasonable back order wait.

The other alternative I'm considering at this point is scrapping the Fuzions and replacing all four tires with a matched set of the relatively new Goodyear F1 All Season. This seems like it might be the safest route for my wife's daily use in a temperate 4-season climate, with winters where temperatures in the 30's are not uncommon and we have occasional ice and minimal snow.

Having lived in Salt Lake City until this summer, she's an experienced snow driver, but that was in a clapped-out Camry.

Thanks again.

Bob

[1schoir]

Eric,

Thanks for the calculator.

I see that the 225/45-17 has the least rolling speed differential from a 205/50-17. That would reduce any effect on ABS sensors and any gyroscopic effect on handling, but what is the effect of a 10mm tread-width increase on handling, if any? First, I understand that the standard front tire size and recommended inflation pressure on the Boxster, when paired with the wider wheel/tread, lower-profile and higher inflation pressure of the rear, is intended, along with the standard suspension and alignment settings, to reduce the tendency of the mid-rear engine, rear-drive car to oversteer. Second, what is the effect of mounting a wider than standard tire on the rim, both on the rim and on the bead and sidewall of the tire?

As I mentioned, the Boxster will be primarily my wife's car. She's a very good driver, but not trained for high performance, rear-drive handling, where the higher limits of the tires can be reached more suddenly and with less warning. Maybe we'll get her that training, but, in the meantime, I don't want to reduce the designed-in understeer safety margin of the car for her real-world driving.

At this point, after some more research, it appears to me that, among the tires theoretically available in the correct size, the Goodyear F1 GS D3 might have the least tread pattern, structure, compound, handling characteristic and wear differential with the Fuzion ZRi's on the back, so I might see if I can order a pair for the front and replace the rears with matching tires when the time comes. I have time with the existing fronts for a reasonable back order wait.

The other alternative I'm considering at this point is scrapping the Fuzions and replacing all four tires with a matched set of the relatively new Goodyear F1 All Season. This seems like it might be the safest route for my wife's daily use in a temperate 4-season climate, with winters where temperatures in the 30's are not uncommon and we have occasional ice and minimal snow.

Having lived in Salt Lake City until this summer, she's an experienced snow driver, but that was in a clapped-out Camry.

Thanks again.

Bob

Bob:

You might also want to consult the most recent Consumer Reports edition... They tested Ultra High Performance Summer and Ultra High Performance All Season tires a couple of weeks ago, and, while I don't follow CR when it comes to things automotive, there is some valuable information there.

They did not test the Goodyear Eagle F1 All Season, but, if I am reading their explanations correctly, they rated the performance of the All Season tires on a scale that can be used to compare them to the Summer tires.

For All Season, they rated the Falken Ziex ZE-912 and the Nitto Neo Gen ZR tires as their top performers among about 15 models IIRC. The price of the two aforementioned sets of tires are about 3/5's or so of the Goodyear All Seasons, but again, there is no direct comparison in that particular report.

Regards, Maurice.