Pros and Cons of low-profile tires?
Pros and Cons of low-profile tires?
(OP)
A colleague and I were debating large diameter rim/low profile tire combinations. I made the statement that the only reason for large diameter rims was to provide sufficient clearances for larger brake components. And that low profile tires were a necessary evil to accomplish this.
He completely disagreed. His belief, is the use of larger rims is for the sole purpose of running low-profile tires. Then he went on to claim alleged performance benefits.
To me it seems that a lower profile tire would provide less straight line traction, and not be as capable of generating high slip angles. The one benefit I can see is that low-profile tires would be less prone to rolling over in a corner, but I’m not sure.
I would appreciate any input in this debate. I leave the ruling in the court of public opinion.
Thanks,
Bryan Carter
He completely disagreed. His belief, is the use of larger rims is for the sole purpose of running low-profile tires. Then he went on to claim alleged performance benefits.
To me it seems that a lower profile tire would provide less straight line traction, and not be as capable of generating high slip angles. The one benefit I can see is that low-profile tires would be less prone to rolling over in a corner, but I’m not sure.
I would appreciate any input in this debate. I leave the ruling in the court of public opinion.
Thanks,
Bryan Carter





RE: Pros and Cons of low-profile tires?
Oh, and styling. It costs about 10 bucks a wheel and less per tyre to move up 1 inch in diameter. How much more do they go for in the showroom?
On the other hand, less progressive breakaway, easier to damage*, heavier, slightly more expensive.
* not necessarily a bad thing, for us. So long as one replacement OEM wheel is cheaper than 4 or 5 aftermarket ones then most people will go for the OEM one.
Cheers
Greg Locock
RE: Pros and Cons of low-profile tires?
Aesthetics aside, how would you compare the performance characteristics of a normal tire to a low-profile one? It would seem to me, that most forms of motorsports do not make use of tires of very low profile (Touring Cars being notable exception).
On a side note, do you think I could trick people into thinking I live in the UK (or Australia) if I said "dampers and tyres" instead of "shocks and tires"?
Thanks,
BC
RE: Pros and Cons of low-profile tires?
Apart from styling (read imitation of race cars), the pros and cons for big dia rim low profile are as Greg said:-
Pros
Improved steering feel
Improved steering response
Lower rolling resistance
Improved sidewall stability under braking
Room for bigger brakes
Less camber distortion when cornering.
Cons
Less progressive breakaway
More susceptable to sidewall damage
Heavier
More expensive
I would add
More susceptable to tram tracking
Greater steering accuracy
Harsher ride
More critical to tyre pressure
Regards
pat
RE: Pros and Cons of low-profile tires?
I have a confidential document here showing the progressive effect of changing a tyre from 155/80 R13 to a 175/70 R13 to a 185/60 R14 to a 195/50 R15.
Side force/slip angle generally improves by about 25% say at 4 degrees. subjective ride&comfort rating drops by 20%(hmmf). subjective dry handling improves by 50% (hmmf). Aquaplaning performance halves.
Cheers
Greg Locock
RE: Pros and Cons of low-profile tires?
Oh Greg, did you mention "styling"? As to the 'profile' my guess is styling because even race tires are usually around 35 series or so and a 20" wheel/tire on a Honda Prelude CAN'T be over a 15 series. Just a guess. The black part is only about an inch off the rim!!!
Hey, it keeps the ecomomy rolling.
Rod
RE: Pros and Cons of low-profile tires?
Exagerated imitation of race cars
Regards
pat
RE: Pros and Cons of low-profile tires?
Certainly agree with all the benefits Greg mentioned, and have plenty of data to back that up. I'd add shorter braking distances to the list, and higher levels of transmitted pattern and road noise.
The less progressive breakaway issue is an interesting one. Certainly a plot of slip angle vs cornering force suggests that. In practice, however, the phenomenon is generally attributed to the higher cornering speed which results from higher levels of driver confidence inspired by the improved response characteristics.
Bryan, you also raise an interesting issue re the validity of comparisons (responded to by Greg). In order to isolate the influence of aspect ratio alone, you need two tyres with all other factors the same - tread compound, construction variables etc etc. Fact is that its nigh on impossible to "correct" the data for these additional variables, as no manufacturer makes such tyres. Then again its probably not important......
Further, tyre manufacturers are increasingly making lower profile tyres tailored for Joe Average replacement market - where life, noise and ride comfort are all important. In these cases many of the benefits of the reduced AR can be sacrificed, and the tyres may not provide superior "performance" cf a high quality, higher aspect ratio tyre. Market forces at work.....
BTW, recent F1 tyre is 55 AR, Indy 40 to 45. Surmise that the reason lower AR's are not preferred is that air volume is required to sustain downforce loads. Of course, this can also be achieved with higher pressures but then you reduce contact area, and and and.......the interesting saga continues !
Comments please ? Cheers
RE: Pros and Cons of low-profile tires?
Rod
RE: Pros and Cons of low-profile tires?
In the OEM & replacement markets the customer is king. If there's sufficient demand, manufacturers will meet it. If customers (OEM and replacement) perceive a benefit in ultra low profile tyres, it will create demand. The benefits of ULP tyres are quite readily measured and demonstrated and have been well covered in previous posts to this forum as well as in numerous texts. It is these benefits (as well as the styling that you identify) that are driving the trend to ULP.
Have fun with it !
RE: Pros and Cons of low-profile tires?
Cars with strut + lower a-arm or trailing arm don't do well at all! You need to play with the camber so when the car is loaded in a turn the tire is square to the road. Old vehicles generally have lots of slack in the bushings too (just popping poly bushes in can show how bad some inaccurate some geometries/manufacturers are)
So dropping some 35 series on your vintage racer isn't often the best soln.
RE: Pros and Cons of low-profile tires?
I believe that on large vehicles such as SUV, the styling is a major factor. The vehicles are getting so large thay just don't "look" right even with P265/70R16.
I guess with the switch away from 70 AR 13" tires on a lot of cars we expect that the tire will take up a certain portion of the profile of a vehicle. Go out and look at the % the tire & wheel is of a car side view vs the % in a large SUV.
RE: Pros and Cons of low-profile tires?
RE: Pros and Cons of low-profile tires?
Rod
PS---Add in the additional $cost$ of a set of ULP tires such as the ones used on the new Ferrari F-50 @ $4000US/set!
RE: Pros and Cons of low-profile tires?
Stability should be a benefit. Not sure why some others are saying bigger rims are heavier, Larger diameter rims with same OD tires (lower AR), should reduce your unsprung weight. The mass of aluminum used to increase the diameter of the wheel will be considerably less than the mass of tire compound that you're doing away with. The lower weight will result in a fuel savings in the long run.
We like to run 22 inch rims on our Semi at the Family ranch as opposed to the 20 inch type. The lower profile tires make a BIG difference when you consider 18 of them at a time. The only concern I see, is cost. The bigger rims and tires are quite a bit more expensive right now (for pick-ups and SUV's anyway)
Have a nice day,
Paul.
RE: Pros and Cons of low-profile tires?
When you increast the rim dia the majority of what you are reducing in the tire is just the sidewall. You have to increase both the spokes and rim portion of the wheel.
RE: Pros and Cons of low-profile tires?
???
that could be kind of important....
Anyone else have data on this?
Jay Maechtlen
RE: Pros and Cons of low-profile tires?
I disagree with the 50% figure in that document, by the way, for such a small change in tyre. There again I disagreed with all the other measures as well!
Another factoid I heard recently is that they have started to include a hinge like feature in the sidewall of low profile tyres. This is to reduce the vertical stiffness and so improve the ride etc. Of course it will also decouple the belt from the hub, so the steering stiffness will drop, which negates the only sensible advantage they have over a higher profile tyre.
Anybody read John Miles' column in Vehicle Dynamics International? Read the last sentence!
Cheers
Greg Locock
RE: Pros and Cons of low-profile tires?
While i agree with your statement, I am about to knitpick a bit about the details. Aluminium is only about twice as heavy as rubber, and that figure is a bit rubbery (excuse the pun).
Cast aluminium is about 2.2 to 2.3, and rubbers are somewhat higher than 1.
There are a number of types of rubbers, as well as various fillers in various quantities. Also tyre sidewalls are a rubber composite with textiles for reinforcement.
The final SG for the composite compound is probably about 1.3
The tyre is probably slightly thicker than an aluminium rim, and the spokes are not disks, so they have less area, but more thickness than the rubber they replace.
My only point is that even though the wheel section is probably heavier than the tyre section it replaces, it is not a simple nor consistent calculation and will vary from case to case, and sometines the result will be a lighter package, but mostly it will be heavier
Regards
pat
RE: Pros and Cons of low-profile tires?
Size OD Weight Load Index
195/55R15 25.3" 35# 84
215/35R18 24.2 42 73
195/60R15 24.2 35 87
205/50R16 24 40 86
205/55R16 24.9 41 89
235/45R17 25.3 46 93
225/40R18 25.1 48 88
235/60R16 27.1 49 99
255/50R17 27.1 53 100
One thing that I didn't see was any ref to the tire's load capability. With some OE applications only having a few% reserve load capacity this can be criticle in some applications.
35 years as Tire Design Eng.
RE: Pros and Cons of low-profile tires?
Norm
RE: Pros and Cons of low-profile tires?
Norm
RE: Pros and Cons of low-profile tires?
Norm
RE: Pros and Cons of low-profile tires?
Cheers
Greg Locock
RE: Pros and Cons of low-profile tires?
LOAD LOAD
INDEX (lbs*)
85 1135
86 1168
87 1201
88 1235
89 1279
90 1323
91 1356
92 1389
93 1433
94 1477
95 1521
. . . that table does not provide any data with respect to inflation pressure. The oldie table that I mentioned above looked something like . . .
Tire..... Inflation pressures (psi)
Size..... ..20.. ..22. ..24. ..26.. ..28. ..30. ..32.. . . .
8.25-15 1250 1310 1380 1440 1500 1560 1620 . . .
(Note that the periods before and after the inflation pressure figures are to hopefully make the table line up in columns)
The general reason I'd like to have that information is because it's useful to have handy, particularly if you're going to deviate from OE tire fitment or get involved in such discussions.
The more specific personal reason revolves around my upcoming need to replace the tires on my 2001 Maxima. Tire size is an issue that's been brought up numerous times by others on the Maxima forum to which I contribute, but so much of the *information* on this topic over there is juvenile, anecdotal, and appearance-oriented that it's all but useless to me.
The short version of the story is that the OE tire is the Bridgestone RE92 in 225/50-17 (I'm ignoring the speed ratings), and the OE wheels are 17 x 7, which I understand to be the minimum width for that tire. Not only that, but the size availability table at www.tirerack.com indicate that there's a dedicated part number for Nissan in that size (I'm guessing that it's for whatever it took to get a 94 load index in that size).
The RE92's aren't very good in the wet as the small sipes start to get shallow even though there's adequate tread depth per the usual measuring methods. So I'm looking for an alternative. There's little to choose from in that size, and most of the tires available in that size are relatively expensive. There's plenty of choice in 235/45-17, though that's at least a half inch outside the rim width guidelines. And there's a wide variety to choose from in 225/45-17, but that size isn't normally associated with LI 94. So I'd be giving up some load capacity at any given pressure, though I should be able to recover that by running a bit more inflation pressure. Yes, I'm willing to trade away ride softness to get there. No, I don't currently have the means to justify scrapping the OE wheels and go aftermarket (besides, I kind of like the OE wheels anyway).
Norm
RE: Pros and Cons of low-profile tires?
At 200 kPA ie 30 psi (guessing what the recommended tyre pressure is) the load capacity is 560 kg
225 45/17 will go on a 7J rim, but is only a 90 load rating, 600 kg at 250 kpa.
For 560 kg capacity you'll need an inflation pressure of 230 kPa on the smaller tyre.
Cheers
Greg Locock
RE: Pros and Cons of low-profile tires?
FWIW, the Nissan-recommended pressures are 32F/32R, though I've adjusted them slightly (to 36-ish/29-ish) in the interest of more nimble turn-in (and with the knowledge that a full 5-passenger + trunk load is a rare occurrence).
Any idea where one might get a copy of those tables?
Norm
RE: Pros and Cons of low-profile tires?
Cheers
Greg Locock
RE: Pros and Cons of low-profile tires?
35 yrs Tire Eng. Designed basic rain Firestone for CART. SCCA & IMSA Pro & Am. Set lap records at 6 different road courses in '89-91.
RE: Pros and Cons of low-profile tires?
I have built an online tyre size calculator which has the useful bonus of showing two calculation to compare two different tyre sizes and/or ARs and/or wheel diameters
I'd like to add a third calculator to show similar data (rolling circumference, diameter, etc) for race tyres. Where can I find a tyre size decoder for race tyre sizes such as 240/515-13?
This is a metric description - the imperial equivalent would be 9.5/20.3-13. I'd like to be able to decode both
The tyre calculator is at
http://www.bolide.co.uk/actions/info.taf?page=tyresizec...
Nick Froome
RE: Pros and Cons of low-profile tires?
anyone remember laws about ground clearance?
no part of the car can be lower than the bottom edge of the wheel at ride height, so if you want a decent size and still be legaly crusing low (important especially to large oem and aftermarket companies) you have to have low profile tires.
So i think the consumers may be emulating the custom car world, you may not have the skill to do a good lowering job but you can buy fancy wheels.
RE: Pros and Cons of low-profile tires?
RE: Pros and Cons of low-profile tires?
But what about the true effect in a curve? does the stiffer sidewall compensate for the greater wt?
RE: Pros and Cons of low-profile tires?
Jason