

| Subject: | Re: Largest diameter wheel. |
| From: | John Rodgers |
| Date: | Sun, 31 Oct 2004 15:33:48 -0600 |
My experiece as well. Note that I too drive an 88 Vanagon based vehicle. Only mine is a GL and therefore lighter in weight than your 88 Westy. However, my last set of tires before the XCA's were the Michelin MXT's - also in size 205-70R14. The only difference I have noted between the two tire types - XCA vs MXT - is that the MXT definitely had a more agrressive tread. On dry pavement I perceive no difference between the two tires, but on wet pavement the difference is significant - in favor of the MXT. Even so, with the MXT no longer being available, I still would recommend the XCA, if one wishes to stick to a 14 inch tire. It is a hell-for-stout tire, having a tall, stiff, sidewall required for our vehicles - a tire with a true 6 ply sidewall with 8 plys on the road, in a load range "D". Difficult to match unless you step up to a 15 inch rim. Regards, John Rodgers 88 GL Driver Todd P. Last wrote: > Good point, as you increase the surface are of the tire, the weight on > each sq. inch. will be reduced - making it easier to break traction. > Wider tires also tend to make the contact patch more rectangular > (shorter front to back) compared to a smaller tire (with the vehicle > weight constant.). > > I have Michelin XCA's as well and agree, they are great dry tires and > wear like steel. (I have 25K miles on mine and they look virtually brand > new as far as treadwear.) > But they are not for wet driving - they slide easily on wet roads > anytime you make abrupt steering or braking inputs. Interestingly, these > are no wider than the tires they replaced on my Van (Michelin MXT's) So > I have to assume that the difference is a combination of the stiffer > sidewalls, harder rubber compound, and hi-way tread. > > Todd > '88 Westy > > > John Rodgers wrote: > >> I cannot address the issue of what size (diameter) rim that can be used, >> but here is a caution. >> >> You do not want a tire on a Vanagon whose road contact surface is really >> wide. While wide tires may look "Macho", they are crap when the chips >> are down and you need serious friction on the road for vehicle control. >> There is a functional relationship between the total surface of the tire >> in contact with the road, and the amount of weight bearing down on that >> tire contact surface. If that relationship is upset by changes in either >> weight or tire contact area, then performance is degraded and may be >> responsible for an accident of the skidding kind. Generally speaking, >> and this is "Generally", a wider tire will have have less traction and >> be more likely to allow the rear of the vehicle to de-stabilize >> resulting in a skid. Not a good thing most of the time. Although I have >> had in my driving career at least two occasions where being able to >> easily induce a skid saved my butt by allowing me to get out of the way. >> The relatively narrow tire specified for the Vanagons was done so for a >> reason. Vanagons really are "trucks" by nature, and as such have widely >> variable weights at different times. A narrow tire with a high load >> rating at the road will be a more controllable vehicle in varying >> weather conditions, but most especially in wet weather conditions. >> >> Be especially careful about the tread type. I run Michelin XCA's >> 205-75R14's. I find that in dry weather it is a great tire. But it is a >> truck tire. And as such it doesn't have a very aggressive tread design. >> The tire relies on that heavy load ratios of the bigger trucks for the >> friction it needs for stopping and also to avoid skidding. My vanagon >> simply doesn't have the weight for the tread type. Consequently I have >> to be more aware and more careful when driving in wet weather. Don't get >> me wrong. I love the tire, but it has it's limitations. Less than the >> best aggressive tread is one of those limitations. In this case, with >> the loads I carry, the number of grooves in the tire tread is >> inadequate, consequently the wide rubber between the grooves in the tire >> tend to make the tire want to float on the film of water on the road >> when it is raining - hydroplane - So I have to be careful. More weight >> would force the water out from under the tread. But I don't have more >> weight. What to do, what to do? Increase the number of grooves in the >> tread. This allows the narrower rib of the tread to cut through the >> water, displacing it sideways and into the grooves of the tire, >> resulting is more rubber on the road. Thus the better control. >> >> So it is all a balancing act between rim sized o carry the right, tire, >> sized for the best contact with the road, adjusted for weather type, and >> load. >> >> We take it all sort of for granted, but rim, tire size, tread type, and >> loading are really fascinating subjects and important. >> >> Again, be careful of what you do with tires when you change them. >> >> Regards, >> >> John Rodgers >> 88 GL Driver >> >> jimt wrote: >> >>> I am just looking for the largest diameter wheel that can fit in the >>> wheel >>> well of a 2WD vanagon. And be used of course. Not into adaptors or >>> anything else just the diameter or tire sizes and I will compute the >>> diameter. >>> >>> Height not treadwidth. >>> Thanks >>> >>> ���������������������������������������� >>> jimt >>> Planned insanity is best. >>> Remember that sanity is optional. >>> http://www.tactical-bus.info (tech info) >>> http://www.westydriver.com >>> >>> >>> >>> >> > >
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