Increasing rear tire size on Toro 42 inch Timecutter

[sgkent]

Smaller tires don't require less power, but a smaller diameter tire produces more pulling power at a slower ground speed.

a smaller diameter tire has the same effect as using a lower gear. So yes, a smaller engine with less torque would move a mower easier with a smaller diameter tire assuming that the PTO pulley size, and transmission pulley size are the same. You did say that the transmission et al was the same. Changing tire diameter would be less expensive than building different size PTO arrangements. So if the engineers wanted a low priced unit they would use an engine with less torque, and then put on smaller tires if they found that the torque was inadequate to use the lessor engine combined with the larger diameter tires.

 

[7394]

Plus any change in tire size will require the cutter deck to be adjusted to compensate.

 

[sgkent]

keep in mind that the transmission bears part of the stress, and it converts the energy lost to heat. The fans cool the transmissions. If less power is available, and larger tires are used, the transmission may spin slower causing the fans to deliver an inadequate amount of cooling. It is a stretch but it is a physical possibility. Also, there may be incline requirements when these mowers are made, meaning that they must maintain X RPM climbing Y grade. With a smaller engine it may take smaller tires to maintain that RPM. Think of trying to climb a hill in 4th gear in a VW bus. One has to drop down in the gears to not only have the power but RPM. If the engine turns too slow it loses its air cooling. Only in this case it is possibly both the engine and transmission that are effected if the RPMs fall too low for the amount of heat being generated. It may require putting the larger tires on, measuring things then making a decision if the engine and transmission RPM are adequate at the grades where the machine will be used. However if both the small deck mower and the large deck mower use the same engine then there would be no problem.

 

[slinger2]

Will you be able to adjust the deck height and rake properly after jacking up the rear of the mower like that?

 

[7394]

On Toro 42, mine only had 2 adjustment points. One in middle front & 1 on (IIRC) Left side of rear deck, other side is a fixed link.
That would need to be replaced with an adjustable link to deck.

 

[packardv8]

On Toro 42, mine only had 2 adjustment points. One in middle front & 1 on (IIRC) Left side of rear deck, other side is a fixed link.
That would need to be replaced with an adjustable link to deck.

Not sure I'd agree the fixed link has to be changed until it is proven the two adjustable links lack sufficient travel to level the deck with the larger rear wheels. That may be the case, but it's not a given.

jack vines

 

[7394]

Time will tell..

 

[packardv8]

I ordered the 18x9.5-8. That’s the same diameter but two inches wider than my original. It’s the same wheel/tire assembly used on the Toro 75750 (next size mower up from mine). That mower has the same hydros (2100) as mine. I don’t know what the weight is for the one inch wheel spacers but expect it to be minimal.
The tire/wheel assembly is coming from Mower Parts Group. The wheel spacers from Titan Wheel Accessories.

Did you ever complete this project and what were the results?

jack vines

 

[BudLight72]

Did you ever complete this project and what were the results?

jack vines

Yes I did complete the installation and am extremely pleased with the results. Can’t say that I have identified any negatives from the changes I’ve made. It has provided a noticeable improvement in the overall traction. Especially when wet.

 

[7394]

Cool Beans !